Method for cryogenic tissue ablation

ABSTRACT

Methods of accessing and ablating abnormal epithelium tissue in an alimentary canal are provided. The methods can include steps of (i) inserting an operative element into an alimentary canal such that the proximate to a portion of the alimentary canal having tissue to be ablated; and (ii) using the operative element to apply cryogenic ablation to a site of abnormal tissue.

CROSS-REFERENCE

This application is a continuation application of U.S. patentapplication Ser. No. 10/963,025, filed Oct. 12, 2004, Publication No.2005-0107829, publication date May 19, 2005, which is a divisional ofU.S. patent application Ser. No. 10/247,153, filed Sep. 19, 2002, nowU.S. Pat. No. 6,872,206, which is a divisional of U.S. patentapplication Ser. No. 09/304,737 , filed May 4, 1999, now U.S. Pat. No.6,464,697, which is a continuation-in-part of U.S. patent applicationSer. No. 09/026,296, filed Feb. 19, 1998, now U.S. Pat. No. 6,009,877,which is a continuation-in-part of U.S. patent application Ser. No.08/731,372, filed Oct. 11, 1996, now U.S. Pat. No. 5,964,755, to whichapplications we claim priority under 35 USC §120.

FIELD OF THE INVENTION

In a general sense, the invention is directed to methods for treatinginterior tissue regions of the body. More specifically, the invention isdirected to methods for treating dysfunction in or near the cardia ofthe stomach.

BACKGROUND OF THE INVENTION

The gastrointestinal tract, also called the alimentary canal, is a longtube through which food is taken into the body and digested. Thealimentary canal begins at the mouth, and includes the pharynx,esophagus, stomach, small and large intestines, and rectum. In humanbeings, this passage is about 30 feet (9 meters) long.

Small, ring-like muscles, called sphincters, surround portions of thealimentary canal. In a healthy person, these muscles contract or tightenin a coordinated fashion during eating and the ensuing digestiveprocess, to temporarily close off one region of the alimentary canalfrom another.

For example, a muscular ring called the lower esophageal sphinctersurrounds the opening between the esophagus and the stomach. The loweresophageal sphincter (or LES) is a ring of increased thickness in thecircular, smooth-muscle layer of the esophagus. Normally, the loweresophageal sphincter maintains a high-pressure zone between fifteen andthirty mm Hg above intragastric pressures inside the stomach.

When a person swallows food, muscles of the pharynx push the food intothe esophagus. The muscles in the esophagus walls respond with awavelike contraction called peristalsis. The lower esophageal sphincterrelaxes before the esophagus contracts, and allows food to pass throughto the stomach. After food passes into the stomach, the lower esophagealsphincter constricts to prevent the contents from regurgitating into theesophagus.

The stomach muscles churn the food and digestive juices into a masscalled chyme. Then the muscles squeeze the chyme toward the pyloric(intestinal) end of the stomach by peristaltic waves, which start at thetop of the stomach and move downward. The pyloric sphincter, anotherringlike muscle, surrounds the duodenal opening. The pyloric sphincterkeeps food in the stomach until it is a liquid. The pyloric sphincterthen relaxes and lets some chyme pass into the duodenum.

Dysfunction of a sphincter in the body can lead to internal damage ordisease, discomfort, or otherwise adversely affect the quality of life.For example, if the lower esophageal sphincter fails to functionproperly, stomach acid may rise back into the esophagus. Unlike thestomach, the esophagus has no natural protection against stomach acids.When the stomach contents make contact with the esophagus, heartburn orother disease symptoms, including damage to the esophagus, can occur.

Gastrointestinal reflux disease (GERD) is a common disorder,characterized by spontaneous relaxation of the lower esophagealsphincter. It has been estimated that approximately two percent of theadult population suffers from GERD. The incidence of GERD increasesmarkedly after the age of 40, and it is not uncommon for patientsexperiencing symptoms to wait years before seeking medical treatment.

GERD is both a normal physiologic phenomenon that occurs in the generalpopulation and a pathophysiologic phenomenon that can result in mild tosevere symptoms.

GERD is believed to be caused by a combination of conditions thatincrease the presence of acid reflux in the esophagus. These conditionsinclude transient LES relaxation, decreased LES resting tone, impairedesophageal clearance, delayed gastric emptying, decreased salivation,and impaired tissue resistance. Since the resting tone of the loweresophageal sphincter is maintained by both myogenic (muscular) andneurogenic (nerve) mechanisms, some believe that aberrant electricalsignals in the lower esophageal sphincter or surrounding region of thestomach (called the cardia) can cause the sphincter to spontaneouslyrelax.

Lifestyle factors can also cause increased risk of reflux. Smoking,large meals, fatty foods, caffeine, pregnancy, obesity, body position,drugs, hormones, and paraplegia may all exacerbate GERD. Also, hiatalhernia frequently accompanies severe GERD. The hernia may increasetransient LES relaxation and delay acid clearance due to impairedesophageal emptying. Thus, hiatal hernias may contribute to prolongedacid exposure time following reflux, resulting in GERD symptoms andesophageal damage.

The excessive reflux experienced by patients with GERD overwhelms theirintrinsic mucosal defense mechanisms, resulting in many symptoms. Themost common symptom of GERD is heartburn. Besides the discomfort ofheartburn, reflux results in symptoms of esophageal inflammation, suchas odynophagia (pain on swallowing) and dysphagia (difficultswallowing). The acid reflux may also cause pulmonary symptoms such ascoughing, wheezing, asthma, aspiration pneumonia, and interstitialfibrosis; oral symptoms such as tooth enamel decay, gingivitis,halitosis, and waterbrash; throat symptoms such as a soreness,laryngitis, hoarseness, and a globus sensation; and earache.

Complications of GERD include esophageal erosion, esophageal ulcer, andesophageal stricture; replacement of normal esophageal epithelium withabnormal (Barrett's) epithelium; and pulmonary aspiration.

Treatment of GERD includes drug therapy to reduce or block stomach acidsecretions. Still, daily drug therapy does not eliminate the root causeof the dysfunction.

Invasive abdominal surgical intervention has also been tried withsuccess. One procedure, called Nissen fundoplication, entails invasive,open abdominal surgery. The surgeon wraps the gastric fundis about thelower esophagus, to, in effect, create a new “valve.” Less invasivelaparoscopic techniques have also been tried to emulate Nissenfundoplication, also with success. Still, all surgical interventionentails making an incision into the abdomen and carry with it the usualrisks of abdominal surgery.

SUMMARY OF THE INVENTION

The invention provides improved methods for treating a tissue region ator near the cardia.

According to one aspect of the invention, the methods deploy anelectrode on a support structure in a tissue region at or near thecardia of the stomach. The support structure has a shape that is wellsuited for deployment in the cardia.

In one embodiment, the support structure has a proximal region and adistal region. The proximal region is enlarged in comparison to thedistal region, to thereby better conform to the funnel shape of thecardia. The electrode is carried by the enlarged proximal surface. Thesystems and methods advance the electrode in a path to penetrate thetissue region.

In one embodiment, the systems and methods and couple the electrode to asource of radio frequency energy to ohmically heat tissue and create alesion in the tissue region. It has been discovered that natural healingof the lesion tightens the cardia and adjoining tissue.

The proximally enlarged support structure can assume various shapes,e.g., a pear shape, or a disk shape, or a peanut shape. In oneembodiment, the support structure is expandable into the desired shape.

Features and advantages of the inventions are set forth in the followingDescription and Drawings, as well as in the appended Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an anatomic view of the esophagus and stomach;

FIG. 2 is a diagrammatic view of a system for treating body sphinctersand adjoining tissue regions, which embodies features of the invention;

FIG. 3 is a perspective view, with portions broken away, of a deviceusable in association with the system shown in FIG. 1 having anoperative element for contacting tissue shown in a collapsed condition;

FIG. 4 is a perspective view, with portions broken away, of the deviceshown in FIG. 3, with the operative element shown in an expandedcondition;

FIG. 5 is a perspective view, with portions broken away, of the deviceshown in FIG. 3, with the operative element shown in an expandedcondition and the electrodes extended for use;

FIG. 6 is an enlarged side view of the operative element when collapsed,as also shown in FIG. 3;

FIG. 7 is an enlarged side view of the operative element when expandedand with the electrodes extended for use, as also shown in FIG. 5;

FIG. 8 is an enlarged perspective view of an embodiment the operativeelement, when fully collapsed;

FIG. 9 is a side view of the deployment of a flexible endoscope throughan esophageal introducer into the stomach;

FIG. 10 is an enlarged view of the endoscope shown in FIG. 9,retroflexed for viewing the cardia and lower esophageal sphincter;

FIG. 11 is a side view of the deployment of the device shown in FIG. 3after deployment of the flexible endoscope shown in FIG. 9, placing theoperative element in the region of the lower esophageal sphincter;

FIG. 12 is an enlarged view of the operative element shown in FIG. 11,when placed in the region of the lower esophageal sphincter;

FIG. 13 is an enlarged view of the operative element shown in FIG. 11,when expanded into contact with muscosal tissue in the region of thelower esophageal sphincter;

FIG. 14 is an enlarged view of the operative element shown in FIG. 11,when expanded into contact with muscosal tissue in the region of thelower esophageal sphincter and with the electrodes extended to createlesions in the smooth muscle ring of the lower esophageal sphincter;

FIG. 15 is an enlarged view of the operative element shown in FIG. 11,when placed in the region of the cardia;

FIG. 16 is an enlarged view of the operative element shown in FIG. 11,when expanded into contact with muscosal tissue in the cardia;

FIG. 17 is an enlarged view of the operative element shown in FIG. 11,when expanded into contact with muscosal tissue in the cardia and withthe electrodes extended to create lesions in the smooth muscle of thecardia;

FIG. 18 is an enlarged view of the operative element shown in FIG. 17,when fully deployed for creating lesions in the cardia;

FIG. 19 is an enlarged view of the operative element shown in FIG. 14 orFIG. 17, after being used to form lesions and in the process of beingremoved from the targeted tissue site;

FIG. 20 is a top view of a targeted tissue region in the cardia, showinga desired pattern of lesions;

FIG. 21 is a perspective view of a “pear-shaped” operative elementintended for deployment in the cardia, shown in a collapsed condition;

FIG. 22 is a perspective view of the “pear-shaped” shown in FIG. 21,shown in an expanded condition with the electrodes extended for use inan antegrade orientation;

FIG. 23 is an enlarged view of the operative element shown in FIG. 22,when expanded into contact with muscosal tissue in the cardia and withthe electrodes extended to create lesions in the smooth muscle of thecardia;

FIG. 24 is a perspective view of the “pear-shaped” shown in FIG. 21,shown in an expanded condition with the electrodes extended for use in aretrograde orientation;

FIG. 25 is an enlarged view of the operative element shown in FIG. 24,when expanded into contact with muscosal tissue in the cardia and withthe electrodes extended to create lesions in the smooth muscle of thecardia;

FIG. 26 is an enlarged side view a “disk-shaped” operative elementintended for deployment in the cardia, when expanded into contact withmuscosal tissue in the cardia and with the electrodes extended to createlesions in the smooth muscle of the cardia;

FIGS. 27 and 28 are enlarged side views of operative elements havingdifferent “peanut” shapes intended for deployment in the cardia, whenexpanded into contact with muscosal tissue in the cardia and with theelectrodes extended to create lesions in the smooth muscle of thecardia;

FIG. 29 is an enlarged side view of an operative element expanded intocontact with muscosal tissue in the cardia and with “pig-tail”electrodes extended to create lesions in the smooth muscle of thecardia;

FIG. 30 is an enlarged perspective section view of an electrode having acylindrical cross section;

FIG. 31 is an enlarged perspective section view of an electrode havingan elliptical cross section to resist twisting;

FIG. 32 is an enlarged perspective section view of an electrode having arectilinear cross section to resist twisting;

FIG. 33 is an enlarged side view of an electrode deployed from anoperative element in the region of the lower esophageal sphincter andhaving a collar to control the depth of tissue penetration;

FIG. 34 is a side section view of a stationary spine which comprises aportion of an operative element and which carries a movable electrodefor creating lesion patterns;

FIG. 35 is a side section view of a stationary spine which comprises aportion of an operative element and which carries a pair of movableelectrodes for creating lesion patterns;

FIGS. 36 and 37 are enlarged side views of operative elements deployedin the cardia and having movable spines for positioning either multipleelectrodes or a single electrode in different positions for creatinglesion patterns;

FIG. 38 is an enlarged side view of an operative element that carries asteerable electrode for creating lesions in body sphincters andadjoining tissue;

FIG. 39 is an enlarged side view of an operative element carryingsurface electrodes for treating abnormal epithelial tissue in thegastrointestinal tract, the operative element being shown in a collapsedcondition and deployed in the region of the lower esophageal sphincter;

FIG. 40 is an enlarged side view of the operative element shown in FIG.39 and in an expanded condition contacting the abnormal epithelialtissue for applying ablation energy;

FIG. 41 is a perspective view of an operative element comprising amechanically expandable basket shown in a collapsed condition;

FIG. 42 is a perspective view of the operative element shown in FIG. 41,with the operative element shown in an expanded condition to extend theelectrodes for use;

FIG. 43 is a side view showing a spine of the basket shown in FIG. 41 asit is mechanically flexed for penetrating tissue;

FIG. 44 is a side view of another operative element comprising amechanically expandable basket shown in an expanded condition with theelectrodes extended for use shown;

FIG. 45 is a side view of the operative element shown in FIG. 44 in acollapsed condition;

FIG. 46 is a perspective view of an operative element that is deployedfor use over a flexible endoscope, shown in a collapsed condition;

FIG. 47 is a perspective view of the operative element shown in FIG. 48in an expanded condition and with the electrodes extended for use;

FIG. 48 is an enlarged view of the operative element shown in FIG. 47,when expanded into contact with muscosal tissue in the cardia and withthe electrodes extended to create lesions in the smooth muscle of thecardia;

FIG. 49 is an end view of the operative element taken generally alongline 49-49 in FIG. 48, as viewed from the retroflex endoscope over whichthe operative element is deployed for use;

FIG. 50 is a perspective view of the operative element of the type shownin FIG. 47, deployed over a flexible endoscope, and including atransparent region within the operative element to permit endoscopicviewing from within the operative element;

FIG. 51 is a perspective view of the operative element shown in FIG.50,with the endoscope positioned within the operative element for viewing;

FIG. 52 is an enlarged view of an operative element comprising amechanically expandable basket deployed over a flexible endoscope andwith the electrodes penetrating the lower esophageal sphincter to createlesions;

FIG. 53 is a perspective view of an operative element for treating bodysphincters and adjoining tissue regions, shown in an expanded conditionwith eight electrodes extended for use;

FIG. 54 is a perspective view of an operative element for treating bodysphincters and adjoining tissue regions, shown in an expanded conditionand four closely spaced electrodes extended for use;

FIG. 55 a perspective distal facing view of an operative element fortreating body sphincters and adjoining tissue regions, showing a spinestructure with cooling and aspiration ports located in the spines;

FIG. 56 a perspective proximal facing view of an operative element shownin FIG.56;

FIG. 57 is a perspective view of a handle for manipulating the operativeelement shown in FIGS. 55 and 56;

FIG. 58A a perspective view of an operative element for treating bodysphincters and adjoining tissue regions, shown a spine structure withcooling ports located in the spines and aspiration ports located in aninterior lumen;

FIG. 58B a perspective view of an operative element for treating bodysphincters and adjoining tissue regions, shown a spine structure with anunderlying expandable balloon structure having pin hole ports which weepcooling liquid about the electrodes;

FIG. 59 a perspective view of an operative element for treating bodysphincters and adjoining tissue regions, shown a spine structure withcooling ports located in the spines and an aspiration port located inits distal tip;

FIG. 60 a perspective view of the operative element shown in FIG. 59,deployed over a guide wire that passes through its distal tip;

FIG. 61 is a perspective view of a handle for manipulating the operativeelement over the guide wire, as shown in FIG. 60;

FIG. 62 a perspective view of an operative element for treating bodysphincters and adjoining tissue regions, deployed through an endoscope;

FIG. 63 is a perspective view of an extruded tube that, upon furtherprocessing, will form an expandable basket structure;

FIG. 64 is a perspective view of the extruded tube shown in FIG. 62 withslits formed to create an expandable basket structure;

FIG. 65 is the expandable basket structure formed after slitting thetube shown in FIG. 63;

FIG. 66 is a side section view of the esophagus, showing the folds ofmucosal tissue;

FIG. 67 is a perspective view of a device for treating body sphinctersand adjoining tissue regions, which applies a vacuum to mucosal tissueto stabilize and present the tissue for the deployment of electrodesdelivered by a rotating mechanism;

FIG. 68 is a section view of the rotating mechanism for deployingelectrodes, taken generally along line 68-68 in FIG. 67 with theelectrodes withdrawn;

FIG. 69 is a view of the rotating mechanism shown in FIG. 68, with avacuum applied to muscosal tissue and the electrodes extended;

FIG. 70 is a perspective view of a device for treating body sphinctersand adjoining tissue regions, which applies a vacuum to mucosal tissueto stabilize and present the tissue for the deployment of straightelectrodes;

FIG. 71 is a side section view of the electrode deployment mechanism ofthe device shown in FIG. 70;

FIGS. 72A and 72B are, respectively, left and right perspective views ofan integrated device for treating body sphincters and adjoining tissueregions, and having graphical user interface;

FIG. 73 is a front view of the device shown in FIGS. 72A and 72B showingthe components of the graphical user interface;

FIG. 74 is a view of the graphical user interface shown in FIG. 73showing the Standby screen before connection of a treatment device;

FIG. 75 is a view of the graphical user interface shown in FIG. 73showing the Standby screen after connection of a treatment device;

FIG. 76 is a view of the graphical user interface shown in FIG. 73showing the Standby screen after connection of a treatment device andafter an electrode channel has been disabled by selection;

FIG. 77 is a view of the graphical user interface shown in FIG. 73showing the Ready screen;

FIG. 78 is a view of the graphical user interface shown in FIG. 73showing the Ready screen while priming of cooling liquid takes place;

FIG. 79 is a view of the graphical user interface shown in FIG. 73showing the RF-On screen;

FIG. 80 is a view of the graphical user interface shown in FIG. 73showing the RF-On screen after an electrode channel has been disableddue to an undesired operating condition;

FIG. 81 is a view of the graphical user interface shown in FIG. 73showing the Pause screen;

FIG. 82 is a schematic view of the control architecture that theintegrated device and associated graphical user interface shown in FIGS.72A, 72B, and 73 incorporate; and

FIG. 83 is an anatomic view of the esophagus and stomach, with portionsbroken away and in section, showing the location of a composite lesionpattern effective in treating GERD.

The invention may be embodied in several forms without departing fromits spirit or essential characteristics. The scope of the invention isdefined in the appended claims, rather than in the specific descriptionpreceding them. All embodiments that fall within the meaning and rangeof equivalency of the claims are therefore intended to be embraced bythe claims.

DETAILED DESCRIPTION OF THE INVENTION

This Specification discloses various catheter-based systems and methodsfor treating dysfunction of sphincters and adjoining tissue regions inthe body. The systems and methods are particularly well suited fortreating these dysfunctions in the upper gastrointestinal tract, e.g.,in the lower esophageal sphincter and adjacent cardia of the stomach.For this reason, the systems and methods will be described in thiscontext.

Still, it should be appreciated that the disclosed systems and methodsare applicable for use in treating other dysfunctions elsewhere in thebody, which are not necessarily sphincter-related. For example, thevarious aspects of the invention have application in proceduresrequiring treatment of hemorrhoids, or incontinence, or restoringcompliance to or otherwise tightening interior tissue or muscle regions.The systems and methods that embody features of the invention are alsoadaptable for use with systems and surgical techniques that are notnecessarily catheter-based.

I. Anatomy of the Lower Esophageal Sphincter Region

As FIG. 1 shows, the esophagus 10 is a muscular tube that carries foodfrom the mouth to the stomach 12. The muscles in the walls of theesophagus 10 contract in a wavelike manner, moving the food down to thestomach 12. The interior wall of the esophagus includes glands thatsecrete mucus, to aid in the movement of food by providing lubrication.The human esophagus is about twenty-five centimeters long.

The stomach 12, located in the upper left hand side of the abdomen, laysbetween the esophagus 10 and the small intestine 14. In people and mostanimals, the stomach 12 is a simple baglike organ. A human being'sstomach is shaped much like a J.

The average adult stomach can hold a little over one quart (0.95 liter).The stomach 12 serves as a storage place for food. Food in the stomach12 is discharged slowly into the intestines 14. The stomach 12 alsohelps digest food.

The upper end of the stomach connects with the esophagus 10 at thecardiac notch 16, at the top of the J-shape. The muscular ring calledthe lower esophageal sphincter 18 surrounds the opening between theesophagus 10 and the stomach 12. The funnel-shaped region of the stomach12 immediately adjacent to the sphincter 18 is called the cardia 20. Thecardia 20 comprises smooth muscle. It is not a sphincter.

The lower esophageal sphincter 18 relaxes, or opens, to allow swallowedfood to enter the stomach 12. The lower esophageal sphincter 18,however, is normally closed, to keep the stomach 12 contents fromflowing back into the esophagus 10.

Another sphincter, called the pyloric sphincter 22, surrounds theduodenal opening of the stomach 12. The pyloric sphincter 22 keepsnon-liquid food material in the stomach 12 until it is processed into amore flowable, liquid form. The time that the stomach 12 retains foodvaries. Usually, the stomach 12 empties in three to five hours.

In a person suffering from GERD, the lower esophageal sphincter 18 issubject to spontaneous relaxation. The sphincter 18 opens independent ofthe normal swallowing function. Acidic stomach contents surge upwardinto the esophagus 10, causing pain, discomfort, and damage the mucosalwall of the esophagus 10.

The stomach 12 distends to accommodate various food volumes. Over time,stomach distention can stretch the cardia 20 or otherwise cause loss ofcompliance in the cardia 20. Loss of compliance in the cardia 20 canalso pull the lower esophageal sphincter 18 open when the stomach 12 isdistended, even absent sphincter muscle relaxation. The same undesiredresults occur: acidic stomach contents can surge upward into theesophagus 10 with the attendant undesired consequences.

It should be noted that the views of the esophagus and stomach shown inFIG. 1 and elsewhere in the drawings are not intended to be strictlyaccurate in an anatomic sense. The drawings show the esophagus andstomach in somewhat diagrammatic form to demonstrate the features of theinvention.

II. Systems for Sphincters or Adjoining Tissue Regions

A. System Overview

FIG. 2 shows a system 24 for diagnosing and/or treating dysfunction ofthe lower esophageal sphincter 18 and/or the adjoining cardia 20 of thestomach 12.

The system 24 includes a treatment device 26. The device 26 includes ahandle 28 made, e.g., from molded plastic. The handle 28 carries aflexible catheter tube 30. The catheter tube 30 can be constructed, forexample, using standard flexible, medical grade plastic materials, likevinyl, nylon, poly(ethylene), ionomer, poly(urethane), poly(amide), andpoly(ethylene terephthalate). The handle 28 is sized to be convenientlyheld by a physician, to introduce the catheter tube 30 into theesophagus 10. The details of using the treatment device 28 will bedescribed later.

The handle 28 and the catheter tube 30 can form an integratedconstruction intended for a single use and subsequent disposal as aunit. Alternatively, the handle 28 can comprise a nondisposablecomponent intended for multiple uses. In this arrangement, the cathetertube 30, and components carried at the end of the catheter tube 30 (aswill be described), comprise a disposable assembly, which the physicianreleasably connects to the handle 28 at time of use and disconnects anddiscards after use. The catheter tube 30 can, for example, include amale plug connector that couples to a female plug receptacle on thehandle 28.

The system 24 may include an esophageal introducer 32. The esophagealintroducer 32 is made from a rigid, inert plastic material, e.g.,poly(ethylene) or polyvinyl chloride. As will be described later, theintroducer 32 aids in the deployment of the catheter tube 30 into theesophagus 10 through the mouth and throat of a patient.

Alternatively, the catheter tube 30 may be deployed over a guide wirethrough the patient's mouth and pharynx, and into the esophagus 10,without use of an introducer 32, as will be described later. Stillalternatively, the catheter tube 30 may be passed through the patient'smouth and pharynx, and into the esophagus 10, without use of either aguide wire or introducer 32.

The catheter tube 30 has a distal end 34, which carries an operativeelement 36. The operative element 36 can take different forms and can beused for either therapeutic purposes, or diagnostic purposes, or both.

The catheter tube 30 can carry a protection sheath 472 (see FIG. 2) forthe operative element 36. The sheath 472 slides along the catheter tube30 (as indicated by arrows 473 in FIG. 2) between a forward positionenclosing the operative element 36 and a rearward position free of theoperative element 36. When in the forward position, the sheath 472prevents contact between tissue and the operative element 36, therebyaiding in the deployment and removal of the operative element 36 throughthe patient's mouth and pharynx. When in the rearward position, thesheath 472 frees the operative element 36 for use.

As will be described in greater detail later, the operative element 36can support, for example, a device for imaging body tissue, such as anendoscope, or an ultrasound transducer. The operative element 36 canalso support a device to deliver a drug or therapeutic material to bodytissue. The operative element 36 can also support a device for sensing aphysiological characteristic in tissue, such as electrical activity, orfor transmitting energy to stimulate or form lesions in tissue.

According to the invention, one function that the operative element 36shown in the illustrated embodiment performs is to apply energy in aselective fashion to a targeted sphincter or other body region, which,for the purpose of illustration, are identified as the lower esophagealsphincter 18, or cardia 20, or both. The applied energy creates one ormore lesions, or a prescribed pattern of lesions, below the mucosalsurface of the esophagus 10 or cardia 20. The subsurface lesions areformed in a manner that preserves and protects the mucosal surfaceagainst thermal damage.

It has been discovered that natural healing of the subsurface lesionsleads to a physical tightening of the sphincter 18 and/or adjoiningcardia 20. The subsurface lesions can also result in the interruption ofaberrant electrical pathways that may cause spontaneous sphincterrelaxation. In any event, the treatment can restore normal closurefunction to the sphincter 18.

In this arrangement, the system 24 includes a generator 38 to supply thetreatment energy. In the illustrated embodiment, the generator 38supplies radio frequency energy, e.g., having a frequency in the rangeof about 400 kHz to about 10 mHz. Of course, other forms of energy canbe applied, e.g., coherent or incoherent light; heated or cooled fluid;resistive heating; microwave; ultrasound; a tissue ablation fluid; orcryogenic fluid.

A cable 40 extending from the proximal end of the handle 28 terminateswith an electrical connector 42. The cable 40 is electrically coupled tothe operative element 36, e.g., by wires that extend through theinterior of the handle 28 and catheter tube 30. The connector 42 plugsinto the generator 38, to convey the generated energy to the operativeelement 36.

The system 24 also includes certain auxiliary processing equipment. Inthe illustrated embodiment, the processing equipment comprises anexternal fluid delivery apparatus 44 and an external aspiratingapparatus 46.

The catheter tube 30 includes one or more interior lumens (not shown)that terminate in fittings 48 and 50, located on the handle 28. Onefitting 40 connects to the fluid delivery apparatus 44, to conveyprocessing fluid for discharge by or near the operative element 36. Theother fitting 50 connects to the aspirating apparatus 46, to conveyaspirated material from or near from the operative element 36 fordischarge.

The system 24 also includes a controller 52. The controller 52, whichpreferably includes a central processing unit (CPU), is linked to thegenerator 38, the fluid delivery apparatus 44, and the aspiratingapparatus 46. Alternatively, the aspirating apparatus 46 can comprise aconventional vacuum source typically present in a physician's suite,which operates continuously, independent of the controller 52.

The controller 52 governs the power levels, cycles, and duration thatthe radio frequency energy is distributed to the operative element 36,to achieve and maintain power levels appropriate to achieve the desiredtreatment objectives. In tandem, the controller 52 also governs thedelivery of processing fluid and, if desired, the removal of aspiratedmaterial.

The controller 52 includes an input/output (I/O) device 54. The I/Odevice 54 allows the physician to input control and processingvariables, to enable the controller to generate appropriate commandsignals. The I/O device 54 also receives real time processing feedbackinformation from one or more sensors associated with the operativeelement (as will be described later), for processing by the controller52, e.g., to govern the application of energy and the delivery ofprocessing fluid. The I/O device 54 also includes a graphical userinterface (GUI), to graphically present processing information to thephysician for viewing or analysis. Further details regarding the GUIwill be provided later.

B. Operative Elements

The structure of the operative element 36 can vary. Variousrepresentative embodiments will be described.

(i) Bipolar Devices

In the embodiment shown in FIGS. 3 to 7, the operative element 36comprises a three-dimensional basket 56. The basket 56 includes one ormore spines 58, and typically includes from four to eight spines 58,which are assembled together by a distal hub 60 and a proximal base 62.In FIG. 3, the spines 58 are equally circumferentially spaced apart inside-by-side pairs.

Each spine 58 preferably comprises a flexible tubular body made, e.g.from molded plastic, stainless steel, or nickel titanium alloy. Thecross sectional shape of the spines 58 can vary, possessing, e.g., acircular, elliptical, square, or rectilinear shape. In the illustratedembodiment, the spines 58 possess a rectilinear shape to resisttwisting. Further examples of specific configurations for the spines 58will be provided later.

Each spine 58 can be surrounded by a sleeve 64 (see FIG. 7) that ispreferably textured to impart friction. Candidate materials for thesleeve 64 include knitted Dacron7 material and Dacron7 velour.

Each spine 58 carries an electrode 66 (see FIGS. 5 and 7). In theillustrated embodiment, each electrode 66 is carried within the tubularspine 58 for sliding movement. Each electrode 66 slides from a retractedposition, withdrawn in the spine 58 (shown in FIGS. 3, 4, and 6), and anextended position, extending outward from the spine 58 (see FIGS. 5 and7) through a hole in the spine 58 and sleeve 64.

A push-pull lever 68 on the handle 28 is coupled by one or more interiorwires to the sliding electrodes 66. The lever 68 controls movementelectrodes between the retracted position (by pulling rearward on thelever 68) and the extended position (by pushing forward on the lever68).

The electrodes 66 can be formed from various energy transmittingmaterials. In the illustrated embodiment, for deployment in theesophagus 10 or cardia 20, the electrodes 66 are formed from nickeltitanium. The electrodes 66 can also be formed from stainless steel,e.g., 304 stainless steel, or, as will be described later, a combinationof nickel titanium and stainless steel. The electrodes 66 havesufficient distal sharpness and strength to penetrate a desired depthinto the smooth muscle of the esophageal or cardia 20 wall. The desireddepth can range from about 4 mm to about 5 mm.

To further facilitate penetration and anchoring in the esophagus 10 orcardia 20, each electrode 66 is preferably biased with a bend. Movementof the electrode 66 into the spine 58 overcomes the bias and straightensthe electrode 66.

In the illustrated embodiment (see FIG. 5), each electrode 66 isnormally biased with an antegrade bend (i.e., bending toward theproximal base 62 of the basket 56). Alternatively, each electrode 66 canbe normally biased toward an opposite retrograde bend (i.e., bendingtoward the distal hub 60 of the basket 58).

As FIG. 7 shows, an electrical insulating material 70 is coated aboutthe proximal end of each electrode 66. For deployment in the esophagus10 or cardia 20, the length of the material 70 ranges from about 80 toabout 120 mm. The insulating material 70 can comprise, e.g., aPolyethylene Terephthalate (PET) material, or a polyimide or polyamidematerial. For deployment in the esophagus 10 or cardia 20, eachelectrode 66 preferably presents an exposed, non-insulated conductivelength of about 8 mm, providing an exposed surface area at the distalend of each electrode 66 of preferably about 0.1 mm² to 100 cm².

When the distal end of the electrode 66 penetrating the smooth muscle ofthe esophageal sphincter 18 or cardia 20 transmits radio frequencyenergy, the material 70 insulates the mucosal surface of the esophagus10 or cardia 20 from direct exposure to the radio frequency energy.Thermal damage to the mucosal surface is thereby avoided. As will bedescribed later, the mucosal surface can also be actively cooled duringapplication of radio frequency energy, to further protect the mucosalsurface from thermal damage.

The ratio between exposed and insulated regions on the electrodes 66affects the impedance of the electrodes 66 during use. Generallyspeaking, the larger the exposed region is compared to the insulatedregion, a lower impedance value can be expected, leading to fewerincidences of power shut-offs due to high impedance.

Of course, a greater or lesser number of spines 58 and/or electrodes 66can be present, and the geometric array of the spines 58 and electrodes66 can vary.

In the embodiment shown in FIG. 3, an expandable structure 72 comprisinga balloon is located within the basket 56. The balloon structure 72 canbe made, e.g., from a Polyethylene Terephthalate (PET) material, or apolyamide (non-compliant) material, or a radiation cross-linkedpolyethylene (semi-compliant) material, or a latex material, or asilicone material, or a C-Flex (highly compliant) material.Non-compliant materials offer the advantages of a predictable size andpressure feedback when inflated in contact with tissue. Compliantmaterials offer the advantages of variable sizes and shape conformanceto adjacent tissue geometries.

The balloon structure 72 presents a normally, generally collapsedcondition, as FIGS. 3 and 6 show). In this condition, the basket 56 isalso normally collapsed about the balloon structure 72, presenting a lowprofile for deployment into the esophagus 10.

To aid in the collapse of the basket 56 (see FIG. 8), one end (hub 60 orbase 62) of the basket 56 can be arranged to slide longitudinallyrelative to the other end of the basket 56, which is accordingly keptstationary. A stylet 74 attached to the slidable end of the basket 56(which, in FIG. 8, is the base 62) is controlled, e.g., by a push-pullmechanism on the handle 28. The stylet 74, when pulled, serves to movethe ends 58 and 60 of the basket 56 apart when the balloon structure 72is collapsed. A full collapse of the basket 56 is thereby possible (asFIG. 8 shows) to minimize the overall profile of the basket 56 forpassage through the esophagus 10. The push-pull mechanism can include alock to hold the stylet 74 stationary, to maintain the basket 56 in thefully collapsed condition during deployment.

The catheter tube 30 includes an interior lumen, which communicates withthe interior of the balloon structure 72. A fitting 76 (e.g., asyringe-activated check valve) is carried by the handle 28. The fitting76 communicates with the lumen. The fitting 76 couples the lumen to asyringe 78 (see FIGS. 4 and 5). The syringe 78 injects fluid underpressure through the lumen into the balloon structure 72, causing itsexpansion.

Expansion of the balloon structure 72 urges the basket 56 to open andexpand (as FIGS. 4, 5, and 7 show). The force exerted by the balloonstructure 72, when expanded, is sufficient to exert an opening forceupon the tissue surrounding the basket 56. Preferably, for deployment inthe esophagus 10 or cardia 20, the magnitude of the force exerted by theballoon structure 72 is between about 0.01 to 0.5 lbs.

For deployment in the lower esophageal sphincter 18, the diameter of theballoon structure 72, when expanded, can be optimized at about 2 cm to 3cm. For deployment in the cardia 20, the diameter of the balloonstructure 72, when expanded, can be optimized at about 4 cm to about 6cm.

In the illustrated embodiment, the controller 52 conditions selectedpairs of electrodes 66 to operate in a bipolar mode. In this mode, oneof the electrodes comprises the transmitter and the other electrodecomprises the return for the transmitted energy. The bipolar electrodepairs can comprise adjacent side-by-side electrodes 66 on a given spine,or electrodes 66 spaced more widely apart on different spines.

In the illustrated embodiment (see FIG. 7), each electrode 66 carries atleast one temperature sensor 80. Each electrode can carry twotemperature sensors 80, one to sense temperature conditions near theexposed distal end of the electrode 66, and the other to sensetemperature conditions in the insulated material 70. Preferably, thesecond temperature sensor 80 is located on the corresponding spine 58,which rests against the muscosal surface when the balloon structure 72is inflated.

In use (see FIGS. 9 to 19), the patient lies awake in a reclined orsemi-reclined position. If used, the physician inserts the esophagealintroducer 32 through the throat and partially into the esophagus 10.The introducer 32 is pre-curved to follow the path from the mouth,through the pharynx, and into the esophagus 10. The introducer 32 alsoincludes a mouthpiece 82, on which the patient bites to hold theintroducer 32 in position. The introducer 32 provides an open,unobstructed path into the esophagus 10 and prevents spontaneous gagreflexes during the procedure.

As before explained, the physician need not use the introducer 32. Inthis instance, a simple mouthpiece 82, upon which the patient bites, isused.

The physician preferably first conducts a diagnostic phase of theprocedure, to localize the site to be treated. As FIGS. 9 and 10 show, avisualization device can be used for this purpose. The visualizationdevice can comprise an endoscope 84, or other suitable visualizingmechanism, carried at the end of a flexible catheter tube 86. Thecatheter tube 86 for the endoscope 84 includes measured markings 88along its length. The markings 88 indicate the distance between a givenlocation along the catheter tube 86 and the endoscope 84.

As FIGS. 9 and 10 show, the physician passes the catheter tube 86through the patients mouth and pharynx, and into the esophagus 10, whilevisualizing through the endoscope 84. Relating the alignment of themarkings 88 to the mouthpiece 82, the physician can gauge, in eitherrelative or absolute terms, the distance between the patient's mouth andthe endoscope 84 in the esophagus 10. When the physician visualizes thedesired treatment site (lower esophageal sphincter 18 or cardia 20) withthe endoscope 84, the physician records the markings 88 that align withthe mouthpiece 82.

The physician next begins the treatment phase of the procedure. As FIGS.11 and 12 show, the physician passes the catheter tube 30 carrying theoperative element 36 through the introducer 32. For the passage, theexpandable balloon structure 72 is in its collapsed condition, and theelectrodes 66 are in their retracted position. The physician can keepthe endoscope 84 deployed for viewing the deployment of the operativeelement 36, either separately deployed in a side-by-side relationshipwith the catheter tube 30, or (as will be described later) by deploymentthrough a lumen in the catheter tube 30 or deployment of the structure72 through a lumen in the endoscope 84 itself. If there is not enoughspace for side-by-side deployment of the endoscope 84, the physiciandeploys the endoscope 84 before and after deployment of the structure72.

In the illustrated embodiment, the catheter tube 30 includes measuredmarkings 90 along its length. The measured markings 90 indicate thedistance between a given location along the catheter tube 30 and theoperative element 36. The markings 90 on the catheter tube 30 correspondin spacing and scale with the measured markings along the endoscopecatheter tube 86. The physician can thereby relate the markings 90 onthe catheter tube 30 to gauge, in either relative or absolute terms, thelocation of the operative element 36 inside the esophagus 10. When themarkings 90 indicate that the operative element 36 is at the desiredlocation (earlier visualized by the endoscope 84), the physician stopspassage of the operative element 36. The operative element 36 is nowlocated at the site targeted for treatment.

In FIG. 12, the targeted site is shown to be the lower esophagealsphincter 18. In FIG. 15, the targeted site is shown to be the cardia 20of the stomach 12.

Once located at the targeted site, the physician operates the syringe 78to convey fluid or air into the expandable balloon structure 72. Thestructure 72, and with it, the basket 56, expand, to make intimatecontact with the mucosal surface, either with the sphincter (see FIG.13) or the cardia 20 (FIG. 16). The expanded balloon structure 72 servesto temporarily dilate the lower esophageal sphincter 18 or cardia 20, toremove some or all of the folds normally present in the mucosal surface.The expanded balloon structure 72 also places the spines 58 in intimatecontact with the mucosal surface.

The physician pushes forward on the lever 68 to move the electrodes 66into their extended position. The electrodes 66 pierce and pass throughthe mucosal tissue into the smooth muscle tissue of the lower esophagealsphincter 18 (FIG. 14) or cardia 20 (FIGS. 17 and 18).

The physician commands the controller 52 to apply radio frequency energybetween the transmitting and receiving electrodes 66 in each pair. Theenergy can be applied simultaneously by all pairs of electrodes 66, orin any desired sequence.

The energy ohmically heats the smooth muscle tissue between thetransmitting and return electrodes 66. The controller 52 samplestemperatures sensed by the sensors 80 to control the application ofenergy. When each electrode 66 in a given pair carries at least onetemperature sensor 80, the controller 52 can average the sensedtemperature conditions or select the maximum temperature conditionsensed for control purposes.

The controller 52 processes the sensed temperatures in a feedback loopto control the application of energy. The GUI can also display thesensed temperatures and the applied energy levels. Alternatively, thephysician can manually control the energy levels based upon thetemperature conditions displayed on the GUI.

Preferably, for a region of the lower esophageal sphincter 18 or cardia20, energy is applied to achieve tissue temperatures in the smoothmuscle tissue in the range of 55° C. to 95° C. In this way, lesions cantypically be created at depths ranging from one to four millimetersbelow the muscosal surface. Typical energies range, e.g., between 100and 1000 joules per electrode pair.

It is desirable that the lesions possess sufficient volume to evoketissue-healing processes accompanied by intervention of fibroblasts,myofibroblasts, macrophages, and other cells. The healing processesresults in a contraction of tissue about the lesion, to decrease itsvolume or otherwise alter its biomechanical properties. The healingprocesses naturally tighten the smooth muscle tissue in the sphincter 18or cardia 20. The bipolar nature of the energy path between theelectrodes 66 creates, for a given amount of energy, lesions of greatervolume than is typically created in a monopolar fashion.

To create greater lesion density in a given targeted tissue area, it isalso desirable to create a pattern of multiple lesions, e.g., in ringsalong the targeted treatment site in the lower esophageal sphincter 18or cardia 20.

Various lesion patterns 92 can be achieved. A preferred pattern (shownin FIG. 20 for the cardia 20) comprises several rings 94 of lesions 96about one centimeter apart, each ring 94 comprising at least eightlesions 96. For example, a preferred pattern 92 comprise six rings 94,each with eight lesions 96. In the cardia 20, as FIG. 20 shows, therings 94 are concentrically spaced about the opening funnel of thecardia 20. In the lower esophageal sphincter 18, the rings 94 areaxially spaced along the esophagus 10.

The physician can create a given ring pattern 92 by expanding theballoon structure 72 and extending the electrodes 66 at the targetedtreatment site, to form a first set of four lesions. The physician thenwithdraws the electrodes 66, collapses the balloon structure 72, androtates the catheter tube 30 by a desired amount. The physician thenagain expands the structure 72 and again extends the electrodes 66, toachieve a second set of four lesions. The physician repeats thissequence until a desired ring 94 of lesions 96 is formed. Additionalrings 94 of lesions 96 can be created by advancing the operative elementaxially, gauging the ring separation by the markings 90 on the cathetertube 30.

Other, more random or eccentric patterns of lesions can be formed toachieve the desired density of lesions within a given targeted site.

The bipolar operative element 36 can be used in the manner described totreat both the cardia 20 and the lower esophageal sphincter 18 in asingle procedure. Alternatively, the operative element 36 can be used inthe manner described to treat either the cardia 20 or the loweresophageal sphincter 18 individually.

In one embodiment, at least one spine 58 (and preferably all spines)includes an interior lumen 98 (see FIG. 7). The fluid delivery apparatus44 conveys processing fluid F through the lumen 98 for discharge at thetreatment site. The processing fluid F can comprise, e.g., saline orsterile water, to cool the mucosal surface while energy is being appliedby the electrode 66 to ohmically heat muscle beneath the surface.

In this arrangement (see FIG. 5), the catheter tube 30 includes a distaltail 100, which extends beyond the hub 60 of the basket 56. An interiorlumen 102 extends through the tail 100 and the interior of the balloonstructure 72 to connect to the fitting 48. The aspirating apparatus 46draws aspirated material and the processing fluid through this lumen 102for discharge. This arrangement provides self-contained aspiration forthe operative element 36.

In an alternative embodiment suited for treatment of the loweresophageal sphincter 18 outside the stomach 12 (see FIG. 11), the mouthpiece 82 of the esophageal introducer 32, if used, includes anaspiration port 104. The aspiration apparatus 46 is coupled to this port104. In this arrangement, processing fluid introduced at the treatmentsite is drawn through the introducer 32 surrounding the catheter tube 30and into the aspiration apparatus 46 for discharge. In this embodiment,the operative element 36 need not include the self contained, interioraspiration lumen 102.

(ii) Structures Shaped for the Cardia

As FIG. 1 shows, the cardia 20 presents a significantly differenttopology than the lower esophageal sphincter 18. First, the surface areaof the cardia 20 is larger than the lower esophageal sphincter 18.Second, the surface area of the cardia 20 expands with distance from thelower esophageal sphincter 18. The cardia 20 is therefore “funnel”shaped, compared to the more tubular shape of the lower esophagealsphincter 18.

The different topologies can be accommodated by using a family ofoperative elements having different shapes. One such operative elementhas a size and geometry better suited for deployment in the loweresophageal sphincter 18 than the cardia 20, if desired). Another suchoperative element has a larger size and different geometry better suitedfor deployment in the cardia 20 than the lower esophageal sphincter.However, it is preferred to provide a single operative element that canbe effectively deployed in both regions.

The location and the orientation of optimal, intimate contact between anoperative element and the targeted tissue also differ in the cardia 20,compared to the lower esophageal sphincter 18. In the lower esophagealsphincter 18, optimal, intimate contact occurs generally about themid-region of the operative element, to thereby conform to the generallytubular shape of the sphincter 18. In the cardia 20, optimal, intimatecontact occurs generally more about the proximal end of operativedevice, to thereby conform to the funnel shape of the cardia 20.

(1) Proximally Enlarged, Shaped Structures

FIGS. 21 to 23 show an operative element 106 having a shaped geometryand electrode configuration well suited for use in the cardia 20. Theoperative element 106 shares many features of the operative element 36shown in FIG. 5, and common reference numbers are thus assigned.

Like the previously described element 36, the operative element 106comprises an array of spines 58 forming a basket 56, which is carried atthe distal end of a catheter tube 30. Like the previously describedelement 36, the operative element 106 includes electrodes 66 on thespines 58 that can be retracted (FIG. 21) or extended (FIG. 22). Asillustrated, the electrodes 66 are likewise bent in an antegradedirection.

Like the previously described element 36, the operative element 106includes an inner balloon structure 72 that expands to open the basket56 and place it in intimate contact with the cardia 20 for extension ofthe electrodes 66.

The balloon structure 72, when expanded, as shown in FIG. 22, possessesa preformed shape achieved e.g., through the use of conventionalthermoforming or blow molding techniques. The structure 72 possesses a“pear” shape, being more enlarged at its proximal end than at its distalend. This preformed pear shape presents an enlarged proximal surface forcontacting the cardia 20 (see FIG. 23). The preformed pear shape betterconforms to the funnel shaped topography of the cardia 20 than acircular shape. The pear shape, when in intimate contact with the cardia20, establishes a secure anchor point for the deployment of theelectrodes 66.

As also shown in FIGS. 22 and 23, the electrodes 66 themselves arerepositioned to take advantage of the pear shape of the underlyingballoon structure 72. The electrodes 66 are positioned proximally closerto the enlarged proximal base of the structure 72 than to its distalend. As FIGS. 24 and 25 show, the proximally located electrodes 66 canalso be bent in a retrograde bent direction on the pear-shaped element106.

In use (as FIGS. 23 and 25 show), the physician deploys the operativeelement 106 into the stomach 12. The physician expands the element 106and then pulls rearward on the catheter tube 30. This places theenlarged proximal base of the structure 106 in contact with the cardia20. The physician next extends the electrodes 66 into the cardia 20 andproceeds with the ablation process. Multiple lesion patterns can becreated by successive extension and retraction of the electrodes,accompanied by rotation and axial movement of the catheter tube 30 toreposition the structure 106.

If enough space is present, the physician can retroflex an endoscope,also deployed in the stomach 12, to image the cardia 20 as deployment ofthe electrodes 66 and lesion formation occur. Typically, however, thereis not enough space for side-by-side deployment of the endoscope, andthe physician views the cardia 20 before and after the lesion groups areformed.

As FIGS. 23 and 25 show, the purposeful proximal shaping of theoperative element 106 and the proximal location of the antegrade orretrograde electrodes 66 make the operative element 106 well suited foruse in the cardia 20.

In FIGS. 22 and 24, the electrodes 66 are not arranged in bipolar pairs.Instead, for purposes of illustration, the electrodes 66 are shownarranged in singular, spaced apart relation. In this arrangement, theelectrodes 66 are intended for monopolar operation. Each electrode 66serves as a transmitter of energy, and an indifferent patch electrode(not shown) serves as a common return for all electrodes 66. It shouldbe appreciated, however, the operative element 106 could include bipolarpairs of electrodes 66 as shown in FIG. 5, if desired.

(2) Disk Shaped Expandable Structures

FIG. 26 shows another operative element 108 shaped for deployment in thecardia 20. This element 108 shares many features with the element 36shown in FIG. 5, and common reference numbers have also been assigned.

In FIG. 26, the expandable balloon structure 72 within the element 108has been preformed, e.g., through the use of conventional thermoformingor blow molding techniques, to present a disk or donut shape. The diskshape also provides an enlarged proximal surface for contacting thecardia 20, to create a secure anchor for the deployment of theelectrodes 66.

The physician deploys the operative element 108 into the stomach 12,preferably imaging the cardia 20 as deployment occurs. The physicianexpands the disk-shaped element 108 and pulls rearward on the cathetertube 30, to place the element 108 in contact with the cardia 20. Thephysician extends the electrodes into the cardia 20 and proceeds withthe ablation process. Lesion patterns are formed by successive extensionand retraction of the electrodes 66, accompanied by rotation and axialmovement of the catheter tube 30.

As FIG. 26 shows, antegrade bent electrodes 66 are proximally mountedabout the disk-shaped expandable element 108. Retrograde bent electrodescould also be deployed.

(3) Complex Shaped Structures Providing Multiple Anchor Points

FIGS. 27 and 28 show another operative element 110 having a geometrywell suited for deployment in the cardia 20. The balloon structure 72within the element 110 is preformed, e.g., through the use ofconventional thermoforming or blow molding techniques, to possess acomplex peanut shape. The complex shape provides multiple surfacecontact regions, both inside and outside the cardia 20, to anchor theelement 110 for deployment of the electrodes 66.

In FIG. 27, a reduced diameter portion 112 of the expanded structure 72contacts the lower esophageal sphincter region. A larger diameter mainportion 114 of the expanded structure 72 rests in intimate contactagainst the cardia 20 of the stomach 12.

In an alternative peanut shaped configuration (see FIG. 28), thestructure 72 includes a first reduced diameter portion 116 to contactthe esophagus 10 above the lower esophageal sphincter 18. The structure72 includes a second reduced portion 118 to contact the lower esophagealsphincter 18 region of the esophagus 10. The structure includes a third,larger diameter main portion 120 to rest in intimate contact against thecardia 20 of the stomach 12.

The peanut shaped configurations shown in FIGS. 27 and 28 providemultiple points of support for operative element 110 both inside andoutside the stomach 12, to thereby stabilize the electrodes.

In FIGS. 27 and 28, antegrade bent electrodes 66 are shown deployed inthe cardia 20. Retrograde bent electrodes could also be deployed.

C. The Electrodes

(i) Electrode Shapes

Regardless of the shape of the operative element and its region ofdeployment in the body, the electrodes 66 can be formed in various sizesand shapes. As FIG. 30 shows, the electrodes 66 can possess a circularcross sectional shape. However, the electrodes 66 preferably possess across section that provides increased resistance to twisting or bendingas the electrodes penetrate tissue. For example, the electrodes 66 canpossess a rectangular cross section, as FIG. 32 shows. Alternatively,the electrodes 66 can possess an elliptical cross section, as FIG. 31shows. Other cross sections, e.g., conical or pyramidal, can also beused to resist twisting.

The surface of the electrode 66 can, e.g., be smooth, or textured, orconcave, or convex. The preceding description describes electrodes 66bent in either an antegrade or retrograde direction over an arc ofninety degrees or less. The bend provides a secure anchorage in tissue.Retraction of the electrodes 66 into the spines 58 overcomes the biasand straightens the electrode 66 when not in use.

In FIG. 29, the electrode 66 is biased toward a “pig-tail” bend, whichspans an arc of greater than ninety degrees. The increased arc of thebend enhances the tissue-gripping force, thereby providing a more secureanchorage in tissue. As before, retraction of the electrodes 66 into thespines 58 overcomes the bias and straightens the electrode 66 when notin use.

A given electrode 66 can comprise a hybrid of materials, e.g., stainlesssteel for the proximal portion and nickel titanium alloy for the distalportion. The nickel titanium alloy performs best in a curved region ofthe electrode 66, due to its super-elastic properties. The use ofstainless steel in the proximal portion can reduce cost, by minimizingthe amount of nickel titanium alloy required.

The different materials may be joined, e.g., by crimping, swaging,soldering, welding, or adhesive bonding, which provide electricalcontinuity between or among the various materials.

One or both of the materials may be flattened to an oval geometry andkeyed together to prevent mutual twisting. In a preferred embodiment,the proximal portion comprises an oval stainless steel tube, into whicha distal curved region having a round cross section and made of nickeltitanium is slipped and keyed to prevent mutual twisting.

(ii) Electrode Penetration Depth

The depth of electrode penetration can also be controlled, to preventpuncture through the targeted tissue region.

In one embodiment, the push-pull lever 68 on the handle 28, whichcontrols movement electrodes 66, can include a ratchet 118 or detentmechanism (see FIG. 3) that provides a tactile indication of electrodeadvancement. For each click of the ratchet mechanism 118 as the lever 68is moved forward or rearward, the physician knows that the electrodeshave traveled a set distance, e.g., 1 mm.

Alternatively, or in combination, the electrode 66 can carry a limitcollar 121 (see FIG. 33). The limit collar 121 contacts surface tissuewhen a set maximum desired depth of electrode penetration has beenreached. The contact between the collar 121 and surface tissue resistsfurther advancement of the electrode 66. The physician senses thecontact between the collar 121 and surface tissue by the increasedresistance to movement of the lever 68. The physician thereby knows thatthe maximum desired depth of tissue penetration has been reached and toextend the electrodes 66 no further.

An electrical measurement can also be made to determine penetration ofan electrode 66 in tissue. For example, by applying electrical energy ata frequency (e.g., 5 kHz) less than that applied for lesion formation,impedance of a given electrode 66 can be assessed. The magnitude of theimpedance varies with the existence of tissue penetration and the depthof tissue penetration. A high impedance value indicates the lack oftissue penetration. The impedance value is lowered to the extent theelectrode penetrates the tissue.

(iii) Movement of Electrodes

As before described, it is desirable to be able to create a pattern ofmultiple lesions to create greater lesion density. The previousdiscussions in this regard were directed to achieving these patterns bysuccessive extension and retraction of the electrodes 66, accompanied byrotation and axial movement of the catheter tube 30.

An alternative embodiment is shown in FIG. 34, which achieves creationof lesion patterns movement without axial and, if desired, rotationalmovement of the catheter tube 30. In this embodiment, the basket 56 hasan array of spines 58, as generally shown, e.g., in FIG. 22 or 24. AsFIG. 34 shows, each spine 58 in the alternative embodiment includes aninner carrier 122 mounted for axial sliding movement within a concentricouter sleeve 124. In this arrangement, a push-pull stylet 126 controlledby another lever on the handle (not shown) axially moves the carrier 122within the outer sleeve 124 (as shown by arrows 125 in FIG. 34).

A tissue penetrating electrode 66 of the type already described issupported by the carrier 122. The electrode 66 can be moved by theoperator (using the handle-mounted lever 68, as shown in FIG. 5) from aretracted position within the carrier 122 and an extended position,projecting from a guide hole 128 in the carrier 122 (which FIG. 34shows). When in the extended position, the electrode 66 also projectsthrough a window 130 in the outer sleeve 124 for tissue penetration. Thewindow 130 has a greater axial length than the guide hole 128. Theextended electrode 66 can thereby be moved by moving the carrier 122 (asshown by arrows 127 in FIG. 34) and thereby positioned in a range ofpositions within the window 130.

For example, in use, the physician moves the carrier 122 so that theguide hole 128 is aligned with the leading edge of the window 130. Thepush-pull stylet 126 can be controlled, e.g., with a detent mechanismthat stops forward advancement or otherwise gives a tactile indicationwhen this alignment occurs. External markings on the handle can alsovisually provide this information. The physician moves the electrodes 66into their respective extended position, to penetrate tissue. Afterenergy sufficient to form a first ring pattern of lesions is applied,the physician withdraws the electrodes 66 into the carriers 122.

The physician now moves the electrodes 66 axially rearward, withoutmoving the catheter tube 30, by pulling the push-pull stylet 126rearward. If desired, the physician can rotate the catheter tube 30 toachieve a different circumferential alignment of electrodes 66. Thedetent mechanism or the like can click or provide another tactileindication that the guide hole 128 in each spine is aligned with a midportion of the respective window 130. Markings on the handle can alsoprovide a visual indication of this alignment. The physician extends theelectrodes 66 through the window 130. This time, the electrodes 66penetrate tissue in a position axially spaced from the first ring ofpenetration. Energy is applied sufficient to form a second ring patternof lesions, which likewise are axially spaced from the first ring. Thephysician withdraws the electrodes 66 into the carriers.

The physician can now move the carriers 122 to move the guide holes 128to a third position at the trailing edge of each window 130, stillwithout axially moving the catheter tube 30. The catheter tube 30 can berotated, if desired, to achieve a different circumferential orientation.The physician repeats the above-described electrode deployment steps toform a third ring pattern of lesions. The physician withdraws theelectrodes 66 into the carriers 122 and withdraws the basket 56,completing the procedure.

As FIG. 35 shows, each carrier 122 can hold more than one electrode 66.In this arrangement, the electrodes 66 on each carrier 122 areextendable and retractable through axially spaced-apart guide holes 128in the carrier 122. In this arrangement, the outer sleeve 124 includesmultiple windows 130 registering with the electrode guide holes 128. Inthis arrangement, the physician is able to simultaneously createmultiple ring patterns. Further, the physician can axially shift theelectrodes 66 and create additional ring patterns by shifting thecarrier 122, and without axial movement of the catheter tube 30.

In the foregoing descriptions, each spine 58 comprises a stationary partof the basket 56. As FIGS. 36 and 37 show, an array of movable spines132, not joined to a common distal hub, can be deployed along theexpandable balloon structure 72. In FIGS. 36 and 37, the expandablestructure 72 is shown to have a disk-shaped geometry and is deployed inthe cardia 20 of the stomach 12. Two movable spines 132 are shown forthe purpose of illustration, but it should be appreciated that fewer orgreater number of movable spines 132 could be deployed.

In this embodiment, the proximal ends of the spines 132 are coupled,e.g., to a push-pull stylet on the handle (not shown). Under control ofthe physician, the spines 132 are advanced to a desired position alongthe structure 72 in the tissue contact region, as shown by arrows 133 inFIGS. 36 and 37. Each movable spine 132 can carry a single electrode 66(as FIG. 37 shows) or multiple electrodes 66 (as shown in FIG. 36).Regardless, each electrode 66 can be extended and retracted relative tothe movable spine 132.

In use, the physician positions the movable spines 132 and deploys theelectrode 66 or electrodes to create a first lesion pattern in thecontact region. By retracting the electrode 66 or electrodes, thephysician can relocate the movable spines 132 to one or more otherpositions (with or without rotating the catheter tube 30). By deployingthe electrode 66 or electrodes in the different positions by moving thespines 132, the physician can form complex lesion patterns in the tissuecontact region without axial movement of the catheter tube 30.

In yet another alternative embodiment (see FIG. 38), an operativeelement 134 can comprise a catheter tube 30 that carries at its distalend a single mono-polar electrode 66 (or a bipolar pair of electrodes),absent an associated expandable structure. The distal end of thecatheter tube 30 includes a conventional catheter steering mechanism 135to move the electrode 66 (or electrodes) into penetrating contact with adesired tissue region, as arrows 137 in FIG. 38 show). The electrode 66can carry a limit collar 121 (as also shown in FIG. 33) to resistadvancement of the electrode 66 beyond a desired penetration depth.Using the operative element 134 shown in FIG. 38, the physician forms adesired pattern of lesions by making a succession of individualmono-polar or bipolar lesions.

(iv) Drug Delivery Through Electrodes

A given electrode 66 deployed by an operative device in a sphincter orother body region can also be used to deliver drugs independent of or asan adjunct to lesion formation. In this arrangement, the electrode 66includes an interior lumen 136 (as FIG. 35 demonstrates for the purposeof illustration).

As before explained, a submucosal lesion can be formed by injecting anablation chemical through the lumen 136, instead of or in combinationwith the application of ablation energy by the electrode.

Any electrode 66 possessing the lumen 136 can also be used to deliverdrugs to the targeted tissue site. For example, tissue growth factors,fibrosis inducers, fibroblast growth factors, or sclerosants can beinjected through the electrode lumen 136, either without or as anadjunct to the application of energy to ablate the tissue. Tissuebulking of a sphincter region can also be achieved by the injection ofcollagen, dermis, cadaver allograft material, or PTFE pellets throughthe electrode lumen 136. If desired, radio frequency energy can beapplied to the injected bulking material to change its physicalcharacteristics, e.g., to expand or harden the bulking material, toachieve a desired effect.

As another example, the failure of a ring of muscle, e.g., the analsphincter or the lower esophageal sphincter 18, called achalasia, canalso be treated using an electrode 66 having an interior lumen 136,carried by an operative device previously described. In thisarrangement, the electrode 66 is deployed and extended into thedysfunctional sphincter muscle. A selected exotoxin, e.g., serotype A ofthe Botulinum toxin, can be injected through the electrode lumen 136 toproduce a flaccid paralysis of the dysfunctional sphincter muscle.

For the treatment of achalasia of a given sphincter, the electrode 66carried by an operative device can also be conditioned to applystimulant energy to nerve tissue coupled to the dysfunctional muscle.The stimulant energy provides an observable positive result (e.g., arelaxation of the sphincter) when targeted nerve tissue is in the tissueregion occupied by the electrode 66. The observable positive resultindicates that position of the electrode 66 should be maintained whileapplying ablation energy to the nerve tissue. Application of the nerveablation energy can permanently eliminate the function of a targetednerve branch, to thereby inactivate a selected sphincter muscle. Furtherdetails of the application of ablation energy to nerve tissue can befound in co-pending application entitled “Systems And Methods ForAblating Discrete Motor Nerve Regions.”

(v) Surface Electrodes

As earlier mentioned, one of the complications of GERD is thereplacement of normal esophageal epithelium with abnormal (Barrett's)epithelium. FIGS. 39 and 40 show an operative element 138 for thetreatment of this condition.

The operative element 138 includes an expandable balloon structure 140carried at the distal end of a catheter tube 30. FIG. 39 shows thestructure 140 deployed in a collapsed condition in the lower esophagealsphincter 18, where the abnormal epithelium tissue condition forms. FIG.40 shows the structure 140 in an expanded condition, contacting theabnormal epithelium tissue.

The structure 140 carries an array of surface electrodes 142. In theillustrated embodiment, the surface electrodes 142 are carried by anelectrically conductive wire 144, e.g., made from nickel-titanium alloymaterial. The wire 144 extends from the distal end of the catheter tube30 and wraps about the structure 140 in a helical pattern. Theelectrodes 142 are electrically coupled to the wire 144, e.g., by solderor adhesive. Alternatively, the balloon structure 140 can have painted,coated, or otherwise deposited on it solid state circuitry to providethe electrical path and electrodes.

Expansion of the balloon structure 140 places the surface electrodes 142in contact with the abnormal epithelium. The application of radiofrequency energy ohmically heats the tissue surface, causing necrosis ofthe abnormal epithelium. The desired effect is the ablation of themucosal surface layer (about 1 mm to 1.5 mm), without substantialablation of underlying tissue. The structure 140 is then collapsed, andthe operative element 138 is removed.

Absent chronic exposure to stomach 12 acid due to continued spontaneousrelaxation of the lower esophageal sphincter 18, subsequent healing ofthe necrosed surface tissue will restore a normal esophageal epithelium.

D. Electrode Structures to Minimize Lesion Overlap

As before described, it is desirable to create one or more symmetricrings of lesions with enough total volume to sufficiently shrink thelower esophageal sphincter or cardia.

FIG. 83 shows a lesion pattern 500 that has demonstrated efficacy intreating GERD. The lesion pattern 500 begins at the Z-line 502, whichmarks the transition between esophageal tissue (which is generally whitein color) and stomach tissue (which is generally pink in color). Thetissue color change at or near the Z-line 502 can be readily visualizedusing an endoscope.

The lower esophageal sphincter 18 (which is about 4 cm to 5 cm inlength) extends above and below the Z-line 502. The Z-line 502 marks thehigh pressure zone of the lower esophageal sphincter 18. In the regionof the Z-line 502, the physician may encounter an overlap of sphinctermuscle and cardia muscle.

As FIG. 83 shows, the lesion pattern 500 extends about 2 cm to 3 cm fromthe Z-line 502 into the cardia 20. The pattern 500 comprises a highdensity of lesion rings 504, spaced apart by about 5 mm, with from fourto sixteen lesions in each ring 504. Five rings 504(1) to 504(5) areshown in FIG. 83. The uppermost ring 504(1) (at or near the Z-line 502)contains eight lesions. The next three rings 504(2) to 504(4) eachcontains twelve lesions. The lower most ring 504(5) contains eightlesions.

The lesion pattern 500 formed in this transition region below the Z-line502 creates, upon healing, an overall desired tightening of thesphincter 18 and adjoining cardia 20 muscle, restoring a normal closurefunction.

It is also believed that the pattern 500 formed in this transitionregion may also create a neurophysiologic effect, as well. The lesionpattern 500 may interrupt infra- and supra-sphincter nerve conduction.The nerve pathway block formed by the lesion pattern 500 may mediatepain due to high pH conditions that accompany GERD and may in other wayscontribute to the overall reduction of spontaneous sphincter relaxationthat the procedure provides.

As before described, rotation or sequential movement of electrodes 66can achieve the desired complex lesion pattern 500. However, insequentially placing the lesions, overlapping lesions can occur.

There are various ways to minimize the incidence of lesion overlap.

(i) Full Ring Electrode Structures

To prevent overlapping lesions, the operative element 36 can, e.g.,carry a number of electrodes 66 sufficient to form all the desiredlesions in a given circumferential ring with a single deployment. Forexample, as FIG. 53 illustrates, when the desired number of lesions fora given ring is eight, the operative element 36 carries eight electrodes66. In this arrangement, the electrodes 66 are equally spaced about thecircumference of the balloon structure 72 on eight spines 58. As beforedescribed, each spine 58 preferably includes an interior lumen with aport 98 to convey a cooling liquid like sterile water into contact withthe mucosal surface of the targeted tissue site.

The generator 38 can include eight channels to supply treatment energysimultaneously to the eight electrodes 66. However, the generator 38that supplies treatment energy simultaneously in four channels to fourelectrodes 66 shown, e.g., in FIG. 22, can be readily configured by thecontroller 52 to supply treatment energy to the eight electrodes 66shown in FIG. 53.

(1) Monopolar/Hottest Temperature Control

In one configuration, pairs of electrodes 66 are shorted together, sothat each channel simultaneously powers two electrodes in a monopolarmode. For simplicity, the shorted electrodes 66 are preferably locatedon, adjacent spines 58, but an adjacent relationship for shortedelectrodes is not essential.

Each electrode 66 carries a temperature sensor 80, coupled to the I/Odevice 54 of the controller 52, as previously described. The controller52 alternatively samples the temperature sensed by the sensors 80 foreach shorted pair of electrodes 66. The controller 52 selects thehottest sensed temperature to serve as the input to control themagnitude of power to both electrodes. Both electrodes receive the samemagnitude of power, as they are shorted together.

(2) Monopolar/Average Temperature Control

In one configuration, pairs of electrodes 66 are shorted together, asdescribed in the previous configuration, so that each channelsimultaneously powers two electrodes in a monopolar mode.

Each electrode 66 carries a temperature sensor 80 and are coupled to theI/O device 54 of the controller 52. In this configuration, thetemperature sensors 80 for each shorted pair of electrodes 66 areconnected in parallel. The controller 52 thus receives as input atemperature that is approximately the average of the temperatures sensedby the sensors 80 for each shorted pair of electrodes 66. The controller52 can include an algorithm to process the input to achieve a weightedaverage. The controller 52 uses this approximate average to control themagnitude of power to both electrodes. As previously stated, bothelectrodes receive the same magnitude of power, as they are shortedtogether.

(3) Monopolar/Switched Control

In this configuration, the controller 52 includes a switch element,which is coupled to each electrode 66 and its associated temperaturesensor 80 independently. In one position, the switch element couples thefour channels of the generator 38 to four of the electrodes (ElectrodeGroup A). In another position, the switch element couples the fourchannels of the generator 38 to another four of the electrodes(Electrode Group B).

The electrodes of Group A could be located on one side of the element36, and the electrodes of Group B could be located on the opposite sideof the element 36. Alternatively, the electrodes 66 of Groups A and Bcan be intermingled about the element 36.

The switch element can switch between Electrode Group A and ElectrodeGroup B, either manually or automatically. The switching can occursequentially or in a rapidly interspersed fashion.

In a sequential mode, Electrode Group A is selected, and the controllersamples the temperatures sensed by each sensor 80 and individuallycontrols power to the associated electrode 66 based upon the sensedtemperature. As tissue heating effects occur as a result of theapplication of energy by Electrode Group A, the other Electrode Group Bis selected. The controller samples the temperatures sensed by eachsensor 80 and individually controls power to the associated electrode 66based upon the sensed temperature. As tissue heating effects occur as aresult of the application of energy by Electrode Group B, the otherElectrode Group A is selected, and so on. This mode may minimizeoverheating effects for a given electrode group.

In an interspersed fashion, the switching between Electrode Groups A andB occurs at greater time intervals between the application of energy,allowing tissue moisture to return to desiccated tissue betweenapplications of energy.

(4) Bipolar Control

In this configuration, the controller 52 conditions four electrodes 66to be transmitters (i.e., coupled to the four channels of the generator38) and conditions the other four electrodes to be returns (i.e.,coupled to the energy return of the generator 38). For simplicity, thetransmitter and return electrodes are preferably located on adjacentspines 58, but this is not essential.

In one arrangement, the four returns can be independent, with no commonground, so that each channel is a true, independent bipolar circuit. Inanother arrangement, the four returns are shorted to provide a single,common return.

For each bipolar channel, the controller 52 samples temperatures sensedby the sensors 80 carried by each electrode 66. The controller 52 canaverage the sensed temperature conditions by each electrode pair. Thecontroller 52 can include an algorithm to process the input to achieve aweighted average. Alternatively, the controller 52 can select themaximum temperature condition sensed by each electrode pair for controlpurposes.

The electrodes 66 used as return-electrodes can be larger than theelectrodes 66 used to transmit the energy. In this arrangement, thereturn electrodes need not carry temperature sensors, as the hottesttemperature will occur at the smaller energy transmitting electrode.

(ii) Partial Ring Electrode Structures

To prevent overlapping lesions, the operative element 36 can, e.g.,carry a number of electrodes 66 sufficient to form, in a singledeployment, a partial arcuate segment of the full circumferential ring.For example, as FIG. 54 illustrates, when the desired number of lesionsfor a given ring is eight, the operative element 36 carries fourelectrodes 66 in a closely spaced pattern spanning 135 degrees on fourspines 58.

In use, the physician deploys the element 36 and creates four lesions ina partial arcuate segment comprising half of the full circumferentialring. The physician then rotates the element 36 one-hundred and eightydegrees and creates four lesions in a partial arcuate segment thatcomprises the other half of the full circumferential ring.

The physician may find that there is less chance of overlapping lesionsby sequentially placing four lesions at 180 intervals, than placing fourlesions at 90 degree intervals, as previously described.

E. Mechanically Expandable Electrode Structures

FIGS. 41 and 42 show an operative element 146 suited for deployment inthe lower esophageal sphincter 18, cardia 20, and other areas of thebody.

In this embodiment, the operative element 146 comprises an expandable,three-dimensional, mechanical basket 148. As illustrated, the basket 148includes eight jointed spines 150, although the number of spines 158can, of course, vary. The jointed spines 150 are pivotally carriedbetween a distal hub 152 and a proximal base 154.

Each jointed spine 150 comprises a body made from inert wire or plasticmaterial. Elastic memory material such as nickel titanium (commerciallyavailable as NITINOLJ material) can be used, as can resilient injectionmolded plastic or stainless steel. In the illustrated embodiment, thejointed spines 150 possess a rectilinear cross sectional shape. However,the cross sectional shape of the spines 150 can vary.

Each jointed spine 150 includes a distal portion 158 and a proximalportion 160 joined by a flexible joint 156. The distal and proximalportions 158 and 160 flex about the joint 156. In the illustratedembodiment, the spine portions 158 and 160 and joint 156 are integrallyformed by molding. In this arrangement, the joint 156 comprises a livinghinge. Of course, the spine portions 158 and 160 can be separatelymanufactured and joined by a mechanical hinge.

In the illustrated embodiment, a pull wire 162 is attached to the distalhub 152 of the basket 148. Pulling on the wire 162 (e.g., by means of asuitable push-pull control on a handle at the proximal end of thecatheter tube 30) draws the hub 152 toward the base 154. Alternatively,a push wire joined to the base 154 can advance the base 154 toward thehub 152. In either case, movement of the base 154 and hub 152 towardeach other causes the spines 150 to flex outward about the joints 156(as FIG. 42 shows). The basket 148 opens, and its maximum diameterexpands.

Conversely, movement of the base 154 and hub 152 away from each othercauses the spines 150 to flex inward about the joints 156. The basket148 closes (as FIG. 41 shows), and its maximum diameter decreases untilit assumes a fully collapsed condition.

Each joint 156 carries an electrode 166. The electrode 166 can comprisean integrally molded part of the spine 150, or it can comprise aseparate component that is attached, e.g. by solder or adhesive, to thespine 150. The electrode material can also be deposited or coated uponthe spine 150.

When the basket 148 is closed, the electrodes 166 nest within the joints156 in a lay flat condition (as FIG. 41 shows), essentially coplanarwith the distal and proximal portions 158 and 160 of the spines 150. Asbest shown in FIG. 43, as the basket 148 opens, flexure of the spines150 about the joints 156 progressively swings the electrodes 166 outwardinto a position for penetrating tissue (designated T in FIG. 43).

As FIG. 43 shows, flexure of a given spine 150 about the associatedjoint 156 swings the electrode 166 in a path, in which the angle oforientation of the electrode 166 relative to the spine progressivelyincreases. As the basket 148 opens, the electrode 166 and the distalportion 158 of the spine 150 become generally aligned in the same plane.Further expansion increases the radial distance between the basket axis164 and distal tip of the electrode 166 (thereby causing tissuepenetration), without significantly increasing the swing angle betweenthe basket axis 164 and the electrode 166 (thereby preventing tissuetear). During the final stages of basket expansion, the electrode 166moves in virtually a linear path into tissue. It is thus possible todeploy the electrode in tissue simultaneously with opening the basket148.

FIGS. 44 and 45 show an operative element 168 comprising a spring biasedbasket 170. In the illustrated embodiment, the distal end of thecatheter tube 30 carries two electrodes 172. A single electrode, or morethan two electrodes, can be carried in the same fashion on the distalend of the catheter tube 30.

The electrodes 172 are formed from a suitable energy transmittingmaterials, e.g. stainless steel. The electrodes 172 have sufficientdistal sharpness and strength to penetrate a desired depth into thesmooth muscle of the esophageal or cardia 20 wall.

The proximal end of each electrode 172 is coupled to the leaf spring174. The leaf spring 174 normally biases the electrodes 172 in anoutwardly flexed condition facing the proximal end of the catheter tube30 (as FIG. 44 shows).

An electrode cover 176 is slidably mounted on the distal end of thecatheter tube 30. A stylet 178 is coupled to the electrode cover 176.The stylet 178 is movable axially along the catheter tube 30, e.g., by alever on the handle at the proximal end of the catheter tube 30.

Pulling on the stylet 178 moves the electrode cover 176 over theelectrodes 172 into the position shown in FIG. 45. On this position, thecover 176 encloses the electrodes 172, pulling them inward against thedistal end of the catheter tube 30. Enclosed within the cover 176, theelectrodes 172 are maintained in a low profile condition for passagethrough the esophagus, e.g., through lower esophageal sphincter 18 andinto a position slightly beyond the surface of the cardia 20.

Pushing on the stylet 178 moves the electrode cover 176 toward adistal-most position beyond the electrodes 172, as shown in FIG. 44.Progressively unconstrained by the cover 176, the electrodes 172 springoutward. The outward spring distance of electrodes 172 depends upon theposition of the cover 176. The electrodes 172 reach their maximum springdistance when the cover 176 reaches its distal-most position, as FIG. 44shows. The distal ends of the electrodes 172 are oriented proximally, topoint, e.g. toward the cardia 20.

With the electrodes 172 sprung outward, the physician pulls rearward onthe catheter tube 30. The electrodes 172 penetrate the cardia 20. Theelectrodes apply energy, forming subsurface lesions in the cardia 20 inthe same fashion earlier described. As FIG. 44 shows, the proximalregion of each electrode 172 is preferably enclosed by an electricalinsulating material 70, to prevent ohmic heating of the mucosal surfaceof the cardia 20.

Upon formation of the lesions, the physician can move the catheter tube30 forward, to advance the electrodes 172 out of contact with the cardia20. By rotating the catheter tube 30, the physician can reorient theelectrodes 172. The physician can also adjust the position of the cover176 to increase or decrease the diameter of the outwardly flexedelectrodes 172. Pulling rearward on the catheter tube 30 causes theelectrodes to penetrate the cardia 20 in their reoriented and/or resizedposition. In this way, the physician can form desired ring or rings oflesion patterns, as already described.

Upon forming the desired lesion pattern, the physician advances theelectrodes 172 out of contact with the cardia 20. The physician movesthe cover 176 back over the electrodes 172 (as FIG. 45 shows). In thiscondition, the physician can withdraw the catheter tube 30 and operativeelement 168 from the cardia 20 and esophagus 10, completing theprocedure.

F. Extruded Electrode Support Structures

FIGS. 63 to 65 show another embodiment of an operative element 216suited for deployment in the lower esophageal sphincter 18, cardia 20,and other areas of the body. In this embodiment, the operative element216 comprises an expandable, extruded basket structure 218 (as FIG. 65shows).

The structure 218 is first extruded (see FIG. 63) as a tube 224 with aco-extruded central interior lumen 220. The tube 224 also includescircumferentially spaced arrays 222 of co-extruded interior wall lumens.Each array 222 is intended to accommodate an electrode 66 and the fluidpassages associated with the electrode 66.

In each array 222, one wall lumen accommodates passage of an electrode66 and related wires. Another lumen in the array 222 is capable ofpassing fluids used, e.g. to cool the mucosal surface. Another lumen inthe array 222 is capable of passing fluids aspirated from the targetedtissue region, if required.

Once extruded (see FIG. 64), the tube wall is cut to form slits 230between the lumen arrays 222. Proximal and distal ends of the tube areleft without slits 230, forming a proximal base 226 and a distal hub228. Appropriate ports 232 are cut in the tube wall between the slits230 to accommodate passage of the electrodes 66 and fluids through thewall lumens. The base 226 is coupled to the distal end of a cathetertube 236.

In the illustrated embodiment (see FIG. 65), a pull wire 234 passingthrough the interior lumen 220 is attached to the distal hub 228.Pulling on the wire 234 (e.g., by means of a suitable push-pull controlon a handle at the proximal end of the catheter tube 236) draws the hub228 toward the base 226 (as FIG. 65 shows). Alternatively, a push wirejoined to the base 226 can advance the base 226 toward the hub 228.

In either case, movement of the base 226 and hub 228 toward each othercauses the tube 224 to flex outward between the slits 230, forming, ineffect, a spined basket. The extruded basket structure 218 opens, andits maximum diameter expands.

Conversely, movement of the base 226 and hub 228 apart causes the tube224 to flex inward between the slits 230. The extruded basket structure218 closes and assumes a collapsed condition.

The central co-extruded lumen 220 is sized to accommodate passage of aguide wire or an endoscope, as will be described in greater detaillater.

G. Cooling and Aspiration

As previously described with respect to the operative element 36 shown,e.g., in FIGS. 5, 7, and 11, it is desirable to cool the mucosal surfacewhile applying energy to ohmically heat muscle beneath the surface. Toaccomplish this objective, the operative element 36 includes a means forapplying a cooling liquid like sterile water to mucosal tissue at thetargeted tissue region and for aspirating or removing the cooling liquidfrom the targeted tissue region.

Various constructions are possible.

(i) Aspiration Through the Spines

In the embodiment shown in FIGS. 55 and 56, the spines 58 extend betweendistal and proximal ends 60 and 62 of the element 36, forming a basket56. Four spines 58 are shown for purpose of illustration. An expandableballoon structure 72 is located within the basket 56, as alreadydescribed. An inflation tube 204 (see FIG. 56) conveys a media to expandthe structure 72 during use.

As FIGS. 55 and 56 show, each spine 58 comprises three tubes 186, 188,and 190. Each tube 186, 188, and 190 has an interior lumen.

The first tube 186 includes an electrode exit port 192 (see FIG. 56).The electrode 66 passes through the exit port 192 for deployment in themanner previously described.

The second tube 188 includes a cooling port 194. The cooling liquidpasses through the cooling port 194 into contact with mucosal tissue.The cooling port 194 is preferably situated on the outside (i.e., tissuefacing) surface of the spine 58, adjacent the electrode exit port 192(see FIG. 56).

The third tube 190 includes an aspiration port 196. Cooling liquid isaspirated through the port 196. The port 196 is preferably situated onthe inside (i.e. facing away from the tissue) surface of the spine 58.

Preferable, at least one of the aspiration ports 196 is located near thedistal end 60 of the element 36, and at least one of the aspirationports 196 is located near the proximal end 62 of the element 36. In theillustrated embodiment, two aspiration ports are located near the distalend 60, on opposite spines 58 (see FIG. 55). Likewise, two aspirationports are located near the proximal end 62, on opposite spines 58 (seeFIG. 56). This arrangement provides for efficient removal of liquid fromthe tissue region.

The electrodes 66 are commonly coupled to the control lever 198 on thehandle 28 (see FIG. 57), to which the catheter tube 30 carrying theelement 36 is connected. The lumen of the second tube 188 communicateswith a port 200 on the handle 28. In use, the port 200 is coupled to asource of cooling fluid. The lumen of the third tube 190 communicateswith a port 202 on the handle 28. In use, the port 202 is coupled to avacuum source. The inflation tube 204 communicates with a port 206 onthe handle 28. The port 206 connects to a source of inflation media,e.g., air in a syringe.

(ii) Interior Aspiration Through an Inner Member

In the alternative embodiment shown in FIG. 58A, the spines 58 (eightare shown for purpose of illustration) each comprises at least two tubes186 and 188. In FIG. 58A, the inflation tube 204 extends through theexpandable balloon structure 72, between the distal and proximal ends 60and 62 of the element 36. Inflation ports 208 communicate with a lumenwithin the tube 204 to convey the expansion media into the structure 72.

The first tube 186 includes the electrode exit port 192, through whichthe electrode 66 passes. The second tube 188 includes the outside facingcooling port 194, for passing cooling liquid into contact with mucosaltissue.

At least one aspiration port 196 communicates with a second lumen in theinflation tube 204. In the illustrated embodiment, two aspiration ports196 are provided, one near the distal end 60 of the element 36, and theother near the proximal end 62 of the element 36.

The element 36 shown in FIG. 58A can be coupled to the handle 28 shownin the FIG. 57 to establish communication between the tubes 188 and 204in the manner already described.

In an alternative embodiment (shown in phantom lines in FIG. 58A), asponge-like, liquid retaining material 320 can be applied about eachspine 58 over the electrode exit port 192 and/or of the cooling port194. The electrode 66 passes through the spongy material 320. Coolingliquid passing through the cooling port 194 is absorbed and retained bythe spongy material 320. The spongy material 320 keeps the coolingliquid in contact with mucosal tissue at a localized positionsurrounding the electrode 66. By absorbing and retaining the flow ofcooling liquid, the spongy material 320 also minimizes the aspirationrequirements. The presence of the spongy material 320 to absorb andretain cooling liquid also reduces the flow rate and volume of coolingliquid required to cool mucosal tissue, and could eliminate the need foraspiration altogether.

In another alternative embodiment, as shown in FIG. 58B, the spines 58(eight are shown for purpose of illustration) each comprises a singletube 186, which includes the electrode exit port 192, through whichincludes the electrode exit port 192, through which the electrode 66passes. As in FIG. 58A, the inflation tube 204 in FIG. 58B extendsthrough the expandable balloon structure 72. Inflation ports 208communicate with a lumen within the tube 204 to convey the expansionmedia into the structure 72.

In this embodiment, the expansion medium comprises the cooling liquid. Apump conveys the cooling liquid into the structure 72. Filling thestructure 72, the cooling liquid causes expansion. The structure 72further includes one or more small pinholes PH near each electrode 66.The cooling liquid “weeps” through the pinholes PH, as the pumpcontinuously conveys cooling liquid into the structure 72. The coolingliquid contacts and cools tissue in the manner previously described.

As in FIG. 58A, at least one aspiration port 196 communicates with asecond lumen in the inflation tube 204 to convey the cooling liquid fromthe treatment site. In FIG. 58B, two aspiration ports 196 are provided,one near the distal end 60 of the element 36, and the other near theproximal end 62 of the element 36.

(iii) Tip Aspiration/Guide Wire

In the alternative embodiment shown in FIG. 59, the spines 58 (four areshown for purpose of illustration) each comprises at least two tubes 186and 188. Like the embodiment shown in FIG. 58, the inflation tube 204 inFIG. 59 extends through the expandable balloon structure 72, between thedistal and proximal ends 60 and 62 of the element 36. Inflation ports208 communicate with a lumen within the tube 204 to convey the expansionmedia into the structure 72.

The first tube 186 includes the electrode exit port 192, through whichthe electrode 66 passes. The second tube 188 includes the outside facingcooling port 194, for passing cooling liquid into contact with mucosaltissue.

In the embodiment shown in FIG. 59, the distal end 60 of the element 36includes an aspiration port 196, which communicates with a second lumenin the inflation tube 204.

The element 36 shown in FIG. 58 can be coupled to the handle 28 shown inthe FIG. 57 to establish communication between the tubes 188 and 204 inthe manner already described.

In the embodiment shown in FIG. 59, the lumen in the inflation tube 204used for aspiration can be alternatively used to pass a guide wire 210,as FIG. 60 shows. The guide wire 210 is introduced through theaspiration port 202 on the handle 28 (as FIG. 61 shows).

Use of a guide wire 210 can obviate the need for the introducer 32previously described and shown in FIG. 9, which may in certainindividuals cause discomfort. In use, the physician passes the smalldiameter guide wire 210 through the patient's mouth and pharynx, andinto the esophagus 10 to the targeted site of the lower esophagealsphincter or cardia. The physician can next pass the operative element36 (see FIG. 60) over the guide wire 210 into position. The physiciancan also deploy an endoscope next to the guide wire 210 for viewing thetargeted site and operative element 36.

Use of the guide wire 210 also makes possible quick exchanges ofendoscope and operative element 36 over the same guide wire 210. In thisarrangement, the guide wire 210 can serve to guide the endoscope andoperative element 36 to the targeted site in quick succession.

G. Vacuum-Assisted Stabilization of Mucosal Tissue

As FIG. 66 shows, mucosal tissue MT normally lays in folds in the areaof the lower esophageal sphincter 18 and cardia 20, presenting a fullyor at least partially closed path. In the preceding embodiments, variousexpandable structures are deployed to dilate the mucosal tissue MT fortreatment. When dilated, the mucosal tissue folds expand and becomesmooth, to present a more uniform surface for submucosal penetration ofthe electrodes 66. The dilation mediates against the possibility that anelectrode 66, when deployed, might slide into a mucosal tissue fold andnot penetrate the underlying sphincter muscle.

(i) Rotational Deployment of Electrodes

FIGS. 67 to 69 show an alternative treatment device 238 suited fordeployment in the lower esophageal sphincter 18, cardia 20, and otherregions of the body to direct electrodes 66 into targeted submucosaltissue regions.

The device 238 includes a handle 248 (see FIG. 67) that carries aflexible catheter tube 242. The distal end of the catheter tube 242carries an operative element 244.

The operative element 244 includes a proximal balloon 246 and a distalballoon 248. The balloons 246 and 248 are coupled to an expansion mediaby a port 276 on the handle 240.

An electrode carrier 250 is located between the balloons 246 and 248. AsFIGS. 67 and 68 show, the carrier 250 includes a generally cylindricalhousing 252 with an exterior wall 268. The housing 252 includes a seriesof circumferentially spaced electrode pods 256. Each pod 256 extendsradially outward of the wall 268 of housing 252.

As FIGS. 68 and 69 show, each pod 256 includes an interior electrodeguide bore 258. The guide bore 258 extends in a curved path through thepod 256 and terminates with an electrode port 262 spaced outward fromthe wall of the housing.

The housing 252 also includes a series of suction ports 260 (see FIGS.68 and 69). Each suction port 260 is located flush with the housing wall268 close to an electrode port 262. The suction ports 260 are coupled toa source of negative pressure through a port 274 on the handle 240.

A driver disk 254 is mounted for rotation within the housing 252.Electrodes 264 are pivotally coupled to the driver disk 254 on pins 266arranged in an equally circumferentially spaced pattern.

The electrodes 264 can be formed from various energy transmittingmaterials, e.g., 304 stainless steel. The electrodes 264 are coupled tothe generator 38, preferable through the controller 52.

The electrodes 264 have sufficient distal sharpness and strength topenetrate a desired depth into the smooth muscle of the esophageal orcardia 20 apply energy from the generator 38.

As previously described with respect to other embodiments, an electricalinsulating material 278 (see FIGS. 68 and 69) is coated about theproximal end of each electrode 264. When the distal end of the electrode264 penetrating the smooth muscle of the esophageal sphincter 18 orcardia 20 transmits radio frequency energy, the material 278 insulatesthe mucosal surface of the esophagus 10 or cardia 20 from directexposure to the radio frequency energy to prevent thermal damage to themucosal surface. As previously described, the mucosal surface can alsobe actively cooled during application of radio frequency energy, tofurther protect the mucosal surface from thermal damage.

Each electrode 264 is biased with a bend, to pass from the pin 266 in anarcuate path through the electrode guide bore 258 in the associated pod256. Rotation of the driver disk 254 in one direction (which isclockwise in FIG. 68) moves the electrodes 264 through the bores 258outward of the carrier 250 (as FIG. 69 shows). Opposite rotation of thedriver disk 254 (which is counterclockwise in FIG. 68) moves theelectrodes 264 through the bores 258 inward into the carrier 250 (asFIGS. 67 and 68 show).

A drive shaft 270 is coupled to the driver disk 254 to affect clockwiseand counterclockwise rotation of the disk 254. A control knob 272 on thehandle 240 (see FIG. 67) is coupled to the drive shaft 254 to extend andretract the electrodes 264.

In use, the carrier 250 is located at the desired treatment site, e.g.,in the region of the lower esophageal sphincter 18. The balloons 246 and248 are expanded to seal the esophagus in the region between theballoons 246 and 248.

A vacuum is then applied through the suction ports 260. The vacuumevacuates air and fluid from the area of the esophageal lumensurrounding the carrier 250. This will cause the surrounding mucosaltissue to be drawn inward against the wall 268 of the housing 252 (seeFIG. 69), to conform and be pulled tightly against the pods 256.

Applying a vacuum to draw mucosal tissue inward against the pods 256causes the tissue to present a surface nearly perpendicular to theelectrode ports 262 (see FIG. 69). Operation of the driver disk 254moves the electrodes 264 through the ports 262, in a direct path throughmucosal tissue and into the underlying sphincter muscle. Due to thedirect, essentially perpendicular angle of penetration, the electrode264 reaches the desired depth in a short distance (e.g., less than 3mm), minimizing the amount of insulating material 278 required.

The application of vacuum to draw mucosal tissue against the pods 256also prevents movement of the esophagus while the electrodes 264penetrate tissue. The counter force of the vacuum resists tissuemovement in the direction of electrode penetration. The vacuum anchorsthe surrounding tissue and mediates against the “tenting” of tissueduring electrode penetration. Without tenting, the electrode 264penetrates mucosal tissue fully, to obtain a desired depth ofpenetration.

(ii) Straight Deployment of Electrodes

FIGS. 70 and 71 show another alternative treatment device 280 suited fordeployment in the lower esophageal sphincter 18, cardia 20, and otherregions of the body to direct electrodes 66 into targeted submucosaltissue regions.

The device 280 includes a handle 282 (see FIG. 70) that carries aflexible catheter tube 284. The distal end of the catheter tube 284carries an operative element 286.

The operative element 286 includes a proximal balloon 288 and a distalballoon 290. The balloons 288 and 290 are coupled to an expansion mediaby a port 292 on the handle 284.

An electrode carrier 294 is located between the balloons 246 and 248.The carrier 294 includes a generally cylindrical housing 296 with anexterior wall 298 (see FIG. 71). The housing 296 includes a series ofcircumferentially and axially spaced recesses 300 in the wall 298 (bestshown in FIG. 70).

As FIG. 71 shows, an electrode guide bore 302 extends through the wall298 and terminates with an electrode port 304 in each recess 300. Theaxis of each guide bore 302 is generally parallel to the plane of thecorresponding recess 300.

The housing 296 also includes a series of suction ports 306, one in eachrecess 300. The suction ports 306 are coupled to a source of negativepressure through a port 308 on the handle 282.

An electrode mount 310 (see FIG. 71) is mounted for axial movementwithin the housing 296. Electrodes 312 are pivotally coupled to themount 310.

The electrodes 312 can be formed from various energy transmittingmaterials, e.g., 304 stainless steel. The electrodes 312 are coupled tothe generator 38, preferable through the controller 52.

The electrodes 312 have sufficient distal sharpness and strength topenetrate a desired depth into the smooth muscle of the esophageal orcardia 20 to apply energy from the generator 38. As previously describedwith respect to other embodiments, an electrical insulating material 314(see FIG. 71) is coated about the proximal end of each electrode 312.

Each electrode 312 is generally straight, to pass from the mount 310through the electrode guide bore 302. Axial movement of the mount 310toward the guide bores 302 extends the electrodes 312 outward into therecesses 300, as FIG.71 shows. Opposite axial movement of the mount 310withdraws the electrodes 312 through the bores 302 inward from recesses300 (as FIG. 70 shows).

A stylet 316 (see FIG. 71) is coupled to the mount 310 to affect axialmovement of the mount 310. A push-pull control knob 318 on the handle282 is coupled to the stylet 316 to extend and retract the electrodes264. Alternatively, a spring loaded mechanism can be used to “fire” themount 310 to deploy the electrodes 312.

In use, the carrier 294 is located at the desired treatment site, e.g.,in the region of the lower esophageal sphincter. The balloons 288 and290 are expanded to seal the esophagus in the region between theballoons 288 and 290.

A vacuum is then applied through the suction ports 292. The vacuumevacuates air and fluid from the area of the esophageal lumensurrounding the carrier 294. This will cause the surrounding mucosaltissue to be drawn inward into the recesses, to conform and be pulledtightly against the recesses 300, as FIG. 71 shows.

Applying a vacuum to draw mucosal tissue inward into the recesses 300causes the tissue to present a surface nearly perpendicular to theelectrode ports 304, as FIG. 71 shows. Operation of the mount 310 movesthe electrodes 312 through the ports 304, in a path through mucosaltissue and into the underlying sphincter muscle that is generallyparallel to the axis of the esophageal lumen.

In the same manner described with regard to the preceding embodiment,the application of vacuum to draw mucosal tissue into the recesses 300also anchors the carrier 294 in the esophagus while the electrodes 312penetrate tissue. Ribs and the like can also be provided in the recesses300 or along the wall 298 of the housing 296 to enhance the tissueanchoring effect. The counter force of the vacuum resists tissuemovement in the direction of electrode penetration. The vacuum anchorsthe surrounding tissue and mediates against the “tenting” of tissueduring electrode penetration. The electrodes 312 penetrates mucosaltissue fully, to obtain a desired depth of penetration.

H. Visualization

Visualization of the targeted tissue site before, during, and afterlesion formation is desirable.

(i) Endoscopy

As earlier shown in FIGS. 9 and 10, a separately deployed endoscope 84,carried by a flexible catheter tube 86, is used to visualize thetargeted site. In this embodiment, the operative element 36 is deployedseparately, by means of a separate catheter tube 30.

In an alternative embodiment (shown in FIGS. 46 to 49), a treatmentdevice 26 is deployed over the same catheter tube 86 that carries theendoscope 84. In effect, this arrangement uses the flexible cathetertube 86 of the endoscope 84 as a guide wire.

In this embodiment, the treatment device 26 can carry any suitableoperative element (which, for this reason, is generically designated OEin FIGS. 46 to 49). As FIGS. 46 and 47 show, the catheter tube 30 passesthrough and beyond the interior of the operative element OE. Thecatheter tube 30 further includes a central lumen 180, which is sized toaccommodate passage of the flexible catheter tube 86 carrying theendoscope 84.

As shown in FIG. 48, once the endoscope 84 is deployed in the mannershown in FIGS. 9 and 10, the operative element OE can be passed over thecatheter tube 86 to the targeted tissue region. In FIG. 48, the targetedregion is shown to be the cardia 20.

In use, the endoscope 86 extends distally beyond the operative elementOE. By retroflexing the endoscope 86, as FIGS. 48 and 49 show, thephysician can continuously monitor the placement of the operativeelement OE, the extension of the electrodes 66, and the other steps ofthe lesion formation process already described.

When the operative element OE includes the expandable balloon structure72 (see FIGS. 50 and 51), the structure 72 and the extent of thecatheter tube 30 passing through it, can be formed of a material that istransparent to visible light. In this arrangement, the physician canretract the endoscope 84 into expandable structure 72 (as FIG. 51shows). The physician can then monitor the manipulation of the operativeelement OE and other steps in the lesion formation process from withinthe balloon structure 72. Any portion of the catheter tube 30 can bemade from a transparent material, so the physician can visualize atother locations along its length.

As FIG. 52 shows, the mechanically expanded basket 148 (shown earlier inFIGS. 41 and 42) can likewise be modified for deployment over thecatheter tube 86 that carries the flexible endoscope 84. In thisarrangement, the interior lumen 180 extends through the catheter tube30, the basket 148, and beyond the basket hub 152. The lumen 180 issized to accommodate passage of the endoscope 84.

In another embodiment (see FIG. 62), the endoscope 84 itself can includean interior lumen 212. A catheter tube 214, like that previously shownin FIG. 38, can be sized to be passed through the interior lumen 212 ofthe endoscope 84, to deploy a mono-polar electrode 66 (or a bipolar pairof electrodes) into penetrating contact with a desired tissue region. AsFIG. 62 shows, the electrode 66 can carry a limit collar 121 to resistadvancement of the electrode 66 beyond a desired penetration depth.

In another embodiment, to locate the site of lower esophageal sphincter18 or cardia 20, a rigid endoscope can be deployed through the esophagusof an anesthetized patient. Any operative element OE can be deployed atthe end of a catheter tube to the site identified by rigid endoscopy, toperform the treatment as described. In this arrangement, the cathetertube on which the operative element is deployed need not be flexible.With an anesthetized patient, the catheter tube that carries theoperative element OE can be rigid.

With rigid endoscopy, the catheter tube can be deployed separately fromthe endoscope. Alternatively, the catheter tube can include an interiorlumen sized to pass over the rigid endoscope.

(ii) Fluoroscopy

Fluoroscopy can also be used to visual the deployment of the operativeelement OE. In this arrangement, the operative element OE is modified tocarry one or more radiopaque markers 182 (as FIG. 24 shows) at one ormore identifiable locations, e.g., at the distal hub 60, or proximalbase 62, or both locations.

With a patient lying on her left side upon a fluoroscopy table, thephysician can track movement of the radiopaque markers 182 to monitormovement and deployment of the operative element OE. In addition, thephysician can use endoscopic visualization, as previously described.

(iii) Ultrasound

The catheter tube can carry an ultrasound transducer 184 (as FIG. 21shows) adjacent the proximal or distal end of the operative element OE.The physician can observe the transesophageal echo as a real time image,as the operative element OE is advanced toward the lower esophagealsphincter 18. The real time image reflects the thickness of theesophageal wall.

Loss of the transesophageal echo marks the passage of the ultrasoundtransducer 184 beyond lower esophageal sphincter 18 into the stomach 12.The physician pulls back on the catheter tube 30, until thetransesophageal echo is restored, thereby marking the situs of the loweresophageal sphincter 18.

With the position of the sphincter localized, the physician can proceedto expand the structure 72, deploy the electrodes 66, and perform thesteps of procedure as already described. Changes in the transesophagealecho as the procedure progresses allows the physician to visualizelesion formation on a real time basis.

I. The Graphical User Interface (GUI)

In the illustrated embodiment (see FIGS. 72A and 72B), the radiofrequency generator 38, the controller 52 with I/O device 54, and thefluid delivery apparatus 44 (for the delivery of cooling liquid) areintegrated within a single housing 400. The I/O device 54 includes inputconnectors 402, 404, and 406. The connector 402 accepts an electricalconnector 408 coupled to a given treatment device TD. The connector 404accepts an electrical connector 410 coupled to a patch electrode 412(for mono-polar operation). The connector 406 accepts a pneumaticconnector 414 coupled to a conventional foot pedal 416. These connectors402, 404, and 406 couple these external devices to the controller 52.The I/O device 54 also couples the controller 54 to an array of membranekeypads 422 and other indicator lights on the housing 400 (see FIG. 73),for entering and indicating parameters governing the operation of thecontroller 52.

The I/O device 54 also couples the controller 52 to a displaymicroprocessor 474, as FIG. 82 shows. In the illustrated embodiment, themicroprocessor 474 comprises, e.g., a dedicated Pentium7-based centralprocessing unit. The controller 52 transmits data to the microprocessor474, and the microprocessor 474 acknowledges correct receipt of the dataand formats the data for meaningful display to the physician. In theillustrated embodiment, the dedicated display microprocessor 474 exertsno control over the controller 52.

In the illustrated embodiment, the controller 52 comprises a 68HC11processor having an imbedded operating system. Alternatively, thecontroller 52 can comprise another style of processor, and the operatingsystem can reside as process software on a hard drive coupled to theCPU, which is down loaded to the CPU during system initialization andstartup.

The display microprocessor 474 is coupled to a graphics display monitor420. The controller 52 implements through the display microprocessor 474a graphical user interface, or GUI 424, which is displayed on thedisplay monitor 420. The GUI 424 can be realized, e.g., as a “C”language program implemented by the microprocessor 474 using the MSWINDOWS™ or NT application and the standard WINDOWS 32 API controls,e.g., as provided by the WINDOWS™ Development Kit, along withconventional graphics software disclosed in public literature.

The display microprocessor 474 is also itself coupled to a data storagemodule or floppy disk drive 426. The display microprocessor 474 can alsobe coupled to a keyboard, printer, and include one or more parallel portlinks and one or more conventional serial RS-232C port links orEthernetJ communication links.

The fluid delivery apparatus 44 comprises an integrated, self primingperistaltic pump rotor 428 with a tube loading mechanism, which arecarried on a side panel of the housing 400. Other types of non-invasivepumping mechanisms can be used, e.g., a syringe pump, a shuttle pump, ora diaphragm pump.

In the illustrated embodiment, the fluid delivery apparatus 44 iscoupled to the I/O device 54 via a pump interface 476. The pumpinterface 476 includes imbedded control algorithms that monitoroperation of the pump rotor 428.

For example, the pump interface 476 can monitor the delivery ofelectrical current to the pump rotor 428, to assure that the rotor 428is operating to achieve a desired flow rate or range of flow ratesduring use, or, upon shut down, the rotor 428 has stopped rotation. Anoptical encoder or magnetic Halls effect monitor can be used for thesame purpose.

Alternatively, a flow rate transducer or pressure transducer, or both,coupled to the pump interface 476, can be placed in line along the pumptubing, or in the treatment device TD itself, to monitor flow rate.

Flow rate information acquired from any one of these monitoring devicescan also be applied in a closed loop control algorithm executed by thecontroller 52, to control operation of the pump rotor 428. The algorithmcan apply proportional, integral, or derivative analysis, or acombination thereof, to control operation of the pump rotor 428.

In the illustrated embodiment, it is anticipated that the physician willrely upon the vacuum source typically present in the physician's suiteas the aspiration apparatus 46. However, it should be appreciated thatthe device 400 can readily integrate the aspiration apparatus 46 byselectively reversing the flow direction of the pump rotor 428 (therebycreating a negative pressure) or by including an additional dedicatedpump rotor or equivalent pumping mechanism to perform the aspirationfunction.

In the illustrated embodiment, the integrated generator 38 has fourindependent radio frequency channels. Each channel is capable ofsupplying up to 15 watts of radio frequency energy with a sinusoidalwaveform at 460 kHz. As before explained, the four channels of thegenerator 38 can operate four electrodes in either a monopolar orbipolar mode. As also explained earlier, the four channels can also beconfigured to operate eight electrodes either in a monopolar mode or abipolar mode.

The integrated controller 52 receives two temperature measurementsthrough the I/O device 54 for each channel, one from the tip of eachelectrode on the treatment device TD, and one from tissue surroundingthe electrode. The controller 52 can regulate power to the electrodes ina close-loop based upon the sensed tip temperature, or the sensed tissuetemperature, or both, to achieve and maintain a targeted tip tissuetemperature at each electrode. The controller 52 can also regulate powerto the pump rotor 428 in a closed-loop based upon the sensed tiptemperature, or the sensed tissue temperature, or both, to achieve andmaintain a targeted tissue temperature at each electrode. Alternatively,or in combination, the physician can manually adjust the power level orpump speed based upon a visual display of the sensed tip and tissuetemperatures.

As FIG. 73 best shows, the membrane keypads 422 and other indicators onthe front panel of the device 400 show the various operationalparameters and operating states and allow adjustments to be made. In theillustrated embodiment, as shown in FIG. 73, the keypads 422 andindicators include:

1. Standby/Ready Button 430, which allows switching from one mode ofoperation to another, as will be described later.

2. Standby/Ready Indicator 432, which displays a green light after thedevice 400 passes a self test upon start up.

3. RF On Indicator 434, which displays a blue light when radio frequencyenergy is being delivered.

4. Fault Indicator 436, which displays a red light when an internalerror has been detected. No radio frequency energy can be delivered whenthe Fault Indicator 436 is illuminated.

5. Target Duration Keys 438, which allow increases and decreases in thetarget power duration at the start or during the course of a procedure.

6. Target Temperature Keys 440, which allow increases and decreases inthe target temperature at the start or during the course of a procedure.

7. Maximum Power Keys 442, which allow increases and decreases in themaximum power setting at the start or during the course of a procedure.

8. Channel Selection Keys 444, which allow selection of any or all powerchannels.

9. Coagulation Level Keys 446, which manually increases and decreasesthe magnitude of the indicated depth of insertion of the electrodeswithin the esophagus. This depth is determined, e.g., by visuallygauging the measured markings along the length of the catheter tube ofthe treatment device TD, as previously described. Alternatively, thecoagulation level can be automatically detected by, e.g., placingoptical, mechanical, or magnetic sensors on the mouth piece 82, whichdetect and differentiate among the measured markings along the cathetertube of the treatment device TD to read the magnitude of the depth ofinsertion.

10. Flow Rate and Priming Keys 448, which allow for selection of threeinternally calibrated flow rates, low (e.g., 15 ml/min), medium (e.g.,30 ml/min), and high (e.g., 45 ml/min). Pressing and holding the “Up”keyactivates the pump at a high flow rate for priming, overruling the otherflow rates until the “Up” key is released.

In the illustrated embodiment, the graphics display monitor 420comprises an active matrix LCD display screen located between themembrane keypads 422 and other indicators on the front panel. The GUI424 is implemented by showing on the monitor 420 basic screen displays.In the illustrated embodiment, these displays signify four differentoperating modes: Start-Up, Standby, Ready, RF-On, and Pause.

(i) Start Up

Upon boot-up of the CPU, the operating system implements the GUI 424.The GUI 424 displays an appropriate start-up logo and title image (notshown), while the controller 52 performs a self-test. A movinghorizontal bar or the like can be displayed with the title image toindicate the time remaining to complete the start-up operation.

(ii) Standby

Upon completion of the start-up operation, the Standby screen isdisplayed, as shown in FIG. 74. No radio frequency energy can bedelivered while the Standby screen is displayed.

There are various icons common to the Standby, Ready, RF-On, and Pausescreens.

The Screen Icon 450 is an icon in the left hand corner of the monitor420, which indicates the operating condition of the treatment device TDand its position inside or outside the esophagus. In FIG. 74, thetreatment device TD is shown to be disconnected and outside theesophagus. Pressing the “Up” priming key 448, to cause cooling liquid toflow through the treatment device TD, causes an animated priming streamPS to be displayed along the treatment device TD in the icon, as FIG. 73shows. The animated priming stream PS is displayed in the Screen Icon450 whenever the pump rotor 428 is operating to indicate the supply ofcooling fluid through the treatment TD.

There are also parameter icons designating target duration 452, targettemperature 454, maximum power 456, channel selection 458, coagulationlevel 460, and flow rate/priming 462. These icons are aligned with,respectively, the corresponding Target Duration Keys 438, TargetTemperature Keys 440, Maximum Power Keys 442, Channel Selection Keys444, Coagulation Level Keys 446, and Flow Rate and Priming Keys 448. Theicons 452 to 462 indicate current selected parameter values. The flowrate/priming icon 462 shows the selected pump speed by highlighting asingle droplet image (low speed), a double droplet image (medium speed),and a triple droplet image (high speed).

There is also a floppy disk icon 464 that is normally dimmed, along withthe coagulation level icon 460, until a floppy disk is inserted in thedrive 426. When a floppy disk is inserted in the drive 426, the icons460 and 464 are illuminated (see FIG. 73), and data is savedautomatically after each application of radio frequency energy (as willbe described later).

There is also an Electrode Icon 466. The Electrode Icon 466 comprises anidealized graphical image, which spatially models the particularmultiple electrode geometry of the treatment device TD selected to bedeployed in the esophagus. As FIG. 74 shows, four electrodes are shownin the graphic image of the Icon 466, which are also spaced apart by 90degrees. This graphic image is intended to indicate that the selectedtreatment device TD has the geometry of the four-electrode configurationshown, e.g., in FIG. 5.

For each electrode, the Icon 466 presents in a spatial display themagnitude of tip temperature as actually sensed (in outside box B1) andthe magnitude of tissue temperatures as actually sensed (in inside boxB2). Until a treatment device TD is connected, two dashes appear in theboxes B1 and B2. The existence of a faulty electrode in the treatmentdevice will also lead to the same display.

The controller 52 prohibits advancement to the Ready screen untilnumeric values register in the boxes B1 and B2, as FIG. 75 shows. Thedisplay of numeric values indicate a functional treatment device TD.

No boxes B1 or B2 will appear in the Icon 466 for a given electrode ifthe corresponding electrode/channel has been disabled using the ChannelSelection Keys 444, as FIG. 76 shows. In the illustrated embodiment, thephysician is able to manually select or deselect individual electrodesusing the Selection Keys 444 in the Standby or Ready Modes, but not inthe RF-On Mode. However, the controller 52 can be configured to allowelectrode selection while in the RF-On Mode, if desired.

While in the Standby Mode, the physician connects the treatment deviceTD to the device 400. The physician couples the source of cooling liquidto the appropriate port on the handle of the device TD (as previouslydescribed) and loads the tubing leading from the source of coolingliquid (e.g., a bag containing sterile water) in the pump rotor 428. Thephysician also couples the aspiration source to the appropriate port onthe handle of the treatment device TD (as also already described). Thephysician also couples the patch electrode 412 and foot pedal 416. Thephysician can now deploy the treatment device TD to the targeted tissueregion in the esophagus, in the manners previously described. Thephysician extends the electrodes through mucosal tissue and intounderlying smooth muscle.

Once the treatment device TD is located at the desired location and theelectrodes are deployed, the physician presses the Standby/Ready Button430 to advance the device 400 from Standby to Ready Mode.

(iii) Ready

In the Ready Mode, the controller 52 commands the generator 38 to applybursts of low level radio frequency energy through each electrodeselected for operation. Based upon the transmission of these low levelbursts of energy by each electrode, the controller 52 derives a localimpedance value for each electrode. The impedance value indicateswhether or nor the given electrode is in desired contact withsubmucosal, smooth muscle tissue. The use of impedance measurements forthis purpose has been previously explained.

As FIG. 77 shows, the Ready screen updates the Screen Icon 450 toindicate that the treatment device TD is connected and deployed in thepatient's esophagus. The Ready screen also intermittently blinks the RFOn Indicator 434 to indicate that bursts of radio frequency energy arebeing applied by the electrodes. The Ready screen also updates theElectrode Icon 466 to spatially display in the inside and outside boxesB1 and B2 the actual sensed temperature conditions. The Ready screenalso adds a further outside box B3 to spatially display the derivedimpedance value for each electrode.

On the Ready screen, instantaneous, sensed temperature readings from thetip electrode and tissue surface, as well as impedance values, arecontinuously displayed in spatial relation to the electrodes the boxesB1, B2, and B3 in the Electrode Icon 466. An “acceptable” colorindicator (e.g., green) is also displayed in the background of box B1 aslong as the tip temperature reading is within the desiredpre-established temperature range (e.g., 15 to 120 C). However, if thetip temperature reading is outside the desired range, the colorindicator changes to an “undesirable” color indicator (e.g., to white),and two dashes appear in box B1 instead of numeric values.

The controller 52 prevents the application of radio frequency energy ifany temperature reading is outside a selected range (e.g., 15 to 120°0C.).

The physician selects the “Up” key of the Flow Rate and Priming Keys 448to operate the pump rotor 428 to prime the treatment device TD withcooling fluid. An animated droplet stream PS is displayed along thetreatment device TD in the Icon 450, in the manner shown in FIG. 75, toindicate the delivery of cooling liquid by the pump rotor 428.

By touching the Target Duration Keys 438, the Target Temperature Keys440, the Maximum Power Keys 442, the Channel Selection Keys 444, theCoagulation Level Keys 446, and the Flow Rate and Priming Keys 448, thephysician can affect changes to the parameter values for the intendedprocedure. The controller 52 automatically adjusts to take these valuesinto account in its control algorithms. The corresponding targetduration icon 452, target temperature icon 454, maximum power icon 456,channel selection icon 458, coagulation level icon 460, and flowrate/priming icon 462 change accordingly to indicate the currentselected parameter values.

When the physician is ready to apply energy to the targeted tissueregion, the physician presses the foot pedal 416. In response, thedevice 400 advances from Ready to RF-On Mode, provided that all sensedtemperatures are within the selected range.

(iv) RF-On

When the foot pedal 416 is pressed, the controller 52 activates the pumprotor 428. Cooling liquid is conveyed through the treatment device TDinto contact with mucosal tissue at the targeted site. At the same time,cooling liquid is aspirated from the treatment device TD in an openloop. During a predetermined, preliminary time period (e.g. 2 to 5seconds) while the flow of cooling liquid is established at the site,the controller 52 prevents the application of radio frequency energy.

After the preliminary time period, the controller 52 applies radiofrequency energy through the electrodes. The RF-On screen, shown in FIG.79, is displayed.

The RF-On screen displays the Screen Icon 450, indicate that thetreatment device TD is connected and deployed in the patient'sesophagus. The flow drop animation PS appears, indicating that coolingis taking place. A flashing radio wave animation RW also appears,indicating that radio frequency energy is being applied. The RF OnIndicator 434 is also continuously illuminated to indicate that radiofrequency energy is being applied by the electrodes.

The RF-On screen also updates the Electrode Icon 466 to display in thebox B1 the actual sensed tip temperature conditions. The RF-On screenalso displays the derived impedance value for each electrode in theboxes B3.

Unlike the Ready or Standby screens, the surface temperature is nolonger displayed in a numerical format in a box B2. Instead, a circle C1is displayed, which is color coded to indicate whether the surfacetemperature is less than the prescribed maximum (e.g., 45° C.). If thesurface temperature is below the prescribed maximum, the circle iscolored an “acceptable” color, e.g., green. If the surface temperatureexceeds the prescribed maximum, the color of the circle changes to a“not acceptable” color, e.g., to red.

Likewise; in addition to displaying numeric values, the boxes B1 and B3are also color coded to indicate compliance with prescribed limits. Ifthe tip temperature is below the prescribed maximum (e.g., 100° C.), thebox B1 is colored, e.g., green. If the tip temperature exceeds theprescribed maximum, the box border thickens and the color of the box B1changes, e.g., to red. If the impedance is within prescribed bounds(e.g., between 25 ohms and 1000 ohms), the box B3 is colored, e.g.,grey. If the impedance is outside the prescribed bounds, the box borderthickens and the color of the box B3 changes, e.g., to red.

If desired, the Electrode Icon 466 can also display in a box or circlethe power being applied to each electrode in spatial relation to theidealized image.

The RF-On screen displays the target duration icon 452, targettemperature icon 454, maximum power icon 456, channel selection icon458, coagulation level icon 460, and flow rate/priming icon 462,indicating the current selected parameter values. The physician canalter the target duration or target temperature or maximum power andpump flow rate through the corresponding selection keys 438, 440, 442,and 448 on the fly, and the controller 52 and GUI instantaneously adjustto the new parameter settings. As before mentioned, in the illustratedembodiment, the controller 52 does not permit change of thechannel/electrode while radio frequency energy is being applied, and,for this reason, the channel selection icon 458 is dimmed.

Unlike the Standby and Ready screens, the RF-On screen also displays areal time line graph 468 to show changes to the temperature profile(Y-axis) over time (X-axis). The RF-On screen also shows a running clockicon 470, which changes appearance to count toward the target duration.In the illustrated embodiment, a digital clock display CD is also shown,indicating elapsed time.

The line graph 468 displays four trending lines to show the minimum andmaximum surface and tip temperature readings from all active electrodes.In the illustrated embodiment, the time axis (X-axis) is scaled to oneof five pre-set maximum durations, depending upon the set targetduration. For example, if the target duration is 0 to 3 minutes, themaximum time scale is 3:30 minutes. If the target duration is 3 to 6minutes, the maximum time scale is 6:30 seconds, and so on.

The line graph 468 displays two background horizontal bars HB1 and HB2of different colors. The upper bar HB1 is colored, e.g., green, and iscentered to the target coagulation temperature with a spread of plus andminus 10° C. The lower bar HB2 is colored, e.g., red, and is fixed at aprescribed maximum (e.g., 40° C.) to alert potential surfaceoverheating.

The line graph 468 also displays a triangle marker TM of a selectedcolor (e.g., red)(see FIG. 80) with a number corresponding to thechannel/electrode that is automatically turned off by the controller 52due to operation outside the selected parameters. As before described,the circle C1 and boxes B1 and B3 for this electrode/channel are alsomodified in the electrode icon 466 when this situation occurs.

The Electrode Icon 466 can graphically display other types of status orconfiguration information pertinent to the treatment device TD. Forexample, the Electrode Icon 466 can display a flashing animation inspatial relation to the idealized electrodes to constantly remind thephysician that the electrode is extended into tissue. The flashinganimation ceases to be shown when the electrode is retracted. Theflashing animation reminds the physician to retract the electrodesbefore removing the treatment device TD. As another example, theElectrode Icon 466 can display another flashing animation when theexpandable structure of the treatment device TD is expanded. Theflashing animation reminds the physician to collapse the electrodesbefore removing the treatment device TD.

(v) Pause

The controller 52 terminates the conveyance of radio frequency ablationenergy to the electrodes and the RF-On screen changes into the Pausescreen (see FIG. 81), due to any of the following conditions (i) targetduration is reached, (ii) all channels/electrodes have an erroneouscoagulation condition (electrode or surface temperature or impedance outof range), or (iii) manual termination of radio frequency energyapplication by pressing the foot pedal 416 or the Standby/Ready Button430.

Upon termination of radio frequency ablation energy, the running clockicon 470 stops to indicate total elapsed time. The controller 52commands the continued supply of cooling liquid through the treatmentdevice TD into contact with mucosal tissue at the targeted site. At thesame time, cooling liquid is aspirated from the treatment device TD inan open loop. This flow of cooling liquid continues for a predeterminedtime period (e.g. 2 to 5 seconds) after the supply of radio frequencyablation energy is terminated, after which the controller 52 stops thepump rotor 428.

During Pause, the controller 52 continues to supply intermittent burstsof low power radio frequency energy to acquire impedance information.

The Pause screen is in most respects similar to the RF-On screen. ThePause screen displays the Screen Icon 450, to indicate that thetreatment device TD is connected and deployed in the patient'sesophagus. The flashing radio wave animation is not present, indicatingthat radio frequency energy is no longer being applied. The RF OnIndicator 434 is, however, intermittently illuminated to indicate thatbursts of radio frequency energy are being applied by the electrodes toacquire impedance information.

The RF-On screen also updates the Electrode Icon 466 to display in theboxes B1 and B3 the actual sensed tip temperature and impedanceconditions. However, no background color changes are registered on thePause screen, regardless of whether the sensed conditions are without oroutside the prescribed ranges.

The Pause screen continues to display the target duration icon 452,target temperature icon 454, maximum power icon 456, channel selectionicon 458, coagulation level icon 460, and flow rate/priming icon 462,indicating the current selected parameter values.

The real time temperature line graph 468 continues to display the fourtrending lines, until the target duration is reached and five additionalseconds elapse, to show the drop off of electrode temperature.

If further treatment is desired, pressing the Standby/Ready button 430returns the device 400 from the Pause back to the Ready mode.

(vi) Procedure Log

As previously described, the floppy disk icon 464 and coagulation levelicon 460 are normally dimmed on the various screens, until a floppy diskis inserted in the drive 426. When a floppy disk is inserted in thedrive 426, the icons 460 and 464 are illuminated, and data is savedautomatically after each application of radio frequency energy.

When the floppy disk is inserted, the controller 52 downloads data tothe disk each time it leaves the RF-On screen, either by default ormanual termination of the procedure. The downloaded data creates aprocedure log. The log documents, by date of treatment and number oftreatments, the coagulation level, the coagulation duration, energydelivered by each electrode, and the coolant flow rate. The procedurelog also records at pre-established intervals (e.g., every 5 seconds)the temperatures of the electrode tips and surrounding tissue,impedance, and power delivered by each electrode. The procedure logpreferably records these values in a spreadsheet format.

The housing 400 can carry an integrated printer, or can be coupledthrough the I/O device 54 to an external printer. The printer prints aprocedure log in real time, as the procedure takes place.

Various features of the invention are set forth in the following claims.

1. A method of accessing and ablating abnormal epithelium tissue in analimentary canal comprising: (i) inserting an operative elementcomprising an inflatable member disposed within a basket into thealimentary canal and proximate to a portion of the alimentary canalhaving tissue to be ablated; (ii) expanding the operative element intocontact with the portion of the alimentary canal having tissue to beablated, and (iii) using cryogenic fluid within the operative element toperform cryogenic ablation to the portion of the alimentary canal havingtissue to be ablated.
 2. The method of claim 1, wherein the abnormalepithelium comprises Barrett's epithelium.
 3. The method of claim 1,wherein the inflatable member comprises a balloon.
 4. The method ofclaim 1, further comprising providing an endoscope carried by a flexiblecatheter and positioned to visualize abnormal tissue in an alimentarycanal.
 5. The method of claim 4, wherein the operative element and theendoscope are separately positioned proximate a portion of thealimentary canal having tissue to be ablated.
 6. The method of claim 4,wherein the operative element is deployed over the catheter carrying theendoscope.
 7. The method of claim 1, wherein abnormal tissue ablationcomprises ablation of the mucosal surface layer of the alimentary canalwithout substantial ablation of the underlying tissue.
 8. The method ofclaim 7, wherein ablation of the mucosal surface layer is to a depth ina range of about 1 mm to 1.5 mm.